Hostage Progress Seen by U.N. Chief : Mideast: Perez de Cuellar says the differences are dwindling, but there is little save rumor and speculation to support his assessment. He summons Israeli officials.

While pressure mounted Tuesday on Israel to make a concession in the dispiriting hostage crisis, U.N. Secretary General Javier Perez de Cuellar described the gap among the opposing parties as dwindling from the width of an ocean to the width of a river.

There was little but rumors and rhetoric, however, to back up his assessment. Most of the speculation focused on a possible show of goodwill in which Israel would free a few of its detainees and the Shiite Muslim extremists would reveal the condition of their Israeli prisoners. This, according to the speculation, would serve as a prelude to a general release of hostages and prisoners.

At U.N. offices in Geneva, the 71-year-old Perez de Cuellar, a man long used to quiet, self-effacing diplomacy, has assumed the role proposed by the kidnapers as the main mediator in the crisis. The secretary general found himself at the center of attention as he announced that he had summoned Israeli officials to a meeting in Geneva today, feeding expectations that a deal was near.

In other developments in the hostage crisis:

* President Bush spoke with the U.N. leader by telephone, telling reporters later that Perez de Cuellar “feels there’s enough movement going on that there’s reason to feel more optimism.” The President, vacationing in Kennebunkport, Me., added: “It’s still murky. It’s still ugly business, but I’m very pleased that we have a secretary general of the U.N. that’s willing to go the extra mile.”

* British Prime Minister John Major added to the pressure on Israel with a letter to Prime Minister Yitzhak Shamir calling for a gesture--the release of a few Arab prisoners--to unlock the impasse.

* Edward Austin Tracy, the second of two long-held Western hostages released in the past week, prepared to fly today to Boston, where he is scheduled to enter a hospital specializing in stress disorders. The former hostage had a reunion with his two daughters Tuesday over a spaghetti dinner at the U.S. military hospital in Wiesbaden, Germany.

In Geneva, Perez de Cuellar kept to his upbeat mood as he met with reporters. He told them he thought a settlement could be negotiated in which the Israelis would release 375 Lebanese Shiite prisoners and a Shiite clergyman, while the captors in Lebanon would release the 10 remaining Western hostages and a handful of Israeli servicemen or otherwise account for the Israelis.

“We know more or less what each side wants,” the secretary general said, “and now it is for me to bridge the gap.” Asked how far apart the contenders were, he replied: “Not that far apart. It is not an ocean. I would say a river.”

“Iran has been very, very useful to me in all this process,” Perez de Cuellar said, adding that he discussed the hostage issue for two hours Monday with Iran’s New York-based ambassador to the United Nations, Kamal Kharazi. Iran has influence with the Lebanese groups holding Western hostages.

Israeli negotiators Uri Lubrani and Ori Slonim were heading to Geneva with a proposal that the overall settlement start with the fundamentalists revealing the condition of seven captured Israeli servicemen. The Times of London reported Tuesday that three of the Israelis were believed to be alive, with one held by the Palestine Liberation Organization and the other two by Hezbollah, the extremist, pro-Iranian Shiite organization close to the kidnapers in Beirut. Other reports have suggested that only one of the seven Israelis may yet be alive.

The British Leader

British Prime Minister Major urged Israel not to wait for information about the missing servicemen, but to release some of its prisoners immediately to keep up the momentum that began with the freeing of two hostages in the past week and the delivery of a letter from the kidnapers to Perez de Cuellar calling for a general exchange of captives.

“We do believe that some immediate gesture by the Israeli government in response to . . . dramatic developments could be enormously helpful in the quest for a total release,” Major wrote to Israeli Prime Minister Shamir.

President Bush

At Kennebunkport, Bush said that even though the United States refuses to engage in negotiations with kidnapers, he had told Perez de Cuellar that “we fully support his efforts . . . in everything he’s trying to do.”

But the President also made it clear that he sympathized with Israel’s demand that its servicemen be released or accounted for. “I can understand Israel’s desire to have that full accounting,” he said.

Unlike the British government, the U.S. government insisted that it was not putting pressure on any of the parties in the negotiations.

“We’re not in a position of making any deals,” State Department spokesman Richard Boucher said at a press briefing. “We don’t urge third parties to make any deals. Words like reciprocate don’t appear in our vocabulary. . . . We don’t get involved in urging specific releases of people at specific steps. It would constitute deals.”

The Ex-Hostage

Meanwhile, Tracy, the 60-year-old American hostage released Sunday, finished two days of psychiatric and medical testing at the U.S. military hospital in Wiesbaden and prepared to return to the United States today for the first time in more than 25 years. A salesman of Arabic translations of Western books, Tracy was a resident of Beirut when he was kidnaped almost five years ago.

After his Air Force plane lands at Hanscomb Air Force Base in Bedford, Mass., Tracy is expected to be reunited with his 83-year-old mother, Doris Tracy, and his sister, Maria Lambert.

Tracy will then enter the Veterans Administration Medical Center in Boston, which specializes in stress disorders caused by harrowing experiences in combat. After being released, Tracy appeared disoriented and appeared to have difficulty completing sentences.

He has not spoken with the press since his arrival in Wiesbaden and has refused to authorize his doctors to release any medical information about him to the press.

Jack Smith, former director of the National Center for Stress Recovery of the Veterans Administration, said that Tracy’s rambling speech could be a sign that he is suffering from stress disorder.

Smith said the rambling can occur in individuals who have been alone and who were likely to have had “internal” dialogues “and are not yet used to having normal conversations where someone else is having to follow your thoughts.”

“It would certainly appear to me that he was hurting, which is not surprising,” Smith said.

The specialist on stress disorder, who is not involved in the official evaluation of Tracy, contrasted his condition with that of John McCarthy, the 34-year-old British hostage released last Thursday. “He had a bounce in his step,” Smith said.

But the specialist had an admonition: “The trap is to say that Mr. McCarthy is OK. We’re seeing someone who’s got bounce, and we’re presuming that he’s fine. And we see a more apparent hurt in Mr. Tracy. But that doesn’t mean that one has pain and the other doesn’t.”

Times staff writers William Tuohy in London, Daniel Williams in Jerusalem and Marlene Cimons, Norman Kempster and Beth Hawkins in Washington contributed to this report.

A Who’s Who of Kidnapers

These are some of the prominent terrorist groups:

Hezbollah (Party of God): This Shiite Muslim fundamentalist group is considered the parent of various radical Shiite groups. It was financed by Iran until the death of the Ayatollah Ruhollah Khomeini in June, 1989. Imad Mughniyah is identified as chief security officer of Hezbollah and as a leader of Islamic Jihad. Called the mastermind of many terrorist acts, he reportedly kidnaped Anglican Church envoy Terry Waite. Sheik Abdel Karim Obeid reportedly is its mentor.

Islamic Jihad (Islamic Holy War): The State Department says it is Hezbollah under a different name. Others regard it as one of several distinct groups linked loosely under the Hezbollah ideological banner. Many intelligence sources believe that it has ties to followers of Sheik Mohammed Hussein Fadlallah, a Shiite cleric who also is frequently cited as a leader of Hezbollah.

Islamic Jihad for the Liberation of Palestine: Thought to include radical Shiites and Palestinian guerrillas, it is probably tied loosely to Hezbollah. It holds Americans Alann Steen and Jesse Turner.

Revolutionary Justice Organization: Some analysts believe that it is Islamic Jihad operating under another name. Others contend that it is a breakaway group that mirrors the power struggle between pragmatists and militants in Iran. It released Edward A. Tracy on Sunday and still holds American hostage Joseph J. Cicippio.

Organization of the Oppressed on Earth: Militant Shiite group claims to have kidnaped Marine Lt. Col. William R. Higgins and then killed him in July, 1989.

Revolutionary Organization of Socialist Muslims: Believed a cover for Palestinian terrorist Abu Nidal’s Fatah-Revolutionary Council. It said it killed British hostage Alec Collett in April, 1986.

Arab Commando Cell: Intelligence sources believe that the group is financed and controlled by Libya. Three of its captives--Peter Kilburn, John Leigh Douglas and Philip Padfield--were executed in April, 1986.

Islamic Liberation Organization: Sunni Muslim fundamentalists kidnaped four Soviet diplomats in 1985 and demanded that Moscow pressure Syria to lift its siege of Tripoli, Lebanon. When the Soviets killed some of its members, the group released its hostages.

Christian Lebanese Forces: The militia of the right-wing, predominantly Maronite Christian Phalange Party, it regards itself as a conventional fighting force rather than a terrorist group. But it reportedly was responsible for the kidnaping and apparent killing of four Iranian diplomats in 1982, an act that many observers believe triggered Lebanon’s subsequent plague of hostage-taking.

Who Is Held--and Where?

Westerners Held

* Five Americans, two Britons, two Germans and one Italian kidnaped in Lebanon.

* Seven Israeli servicemen missing in Lebanon.

Arabs Held

* Sheik Abdel Karim Obeid, a Shiite cleric and a senior Hezbollah official.

* 375 Shiites and Palestinians in Israeli-controlled prisons.

* Brothers Mohammed and Abbas Hamadi, imprisoned in Germany.

* Ali Mohammed Hariri, imprisoned in Switzerland.

* Seven Shiites held on terrorist charges in Spain.

* About 14,000 Palestinian prisoners from the Gaza Strip and occupied West Bank.