Arrival of U.N. Negotiator Raises Hopes for Hostages : Middle East: A Tehran newspaper dispatch reports that two Western captives, an American and a Briton, will be released soon.

New movement on the Beirut hostage crisis was foreshadowed Saturday by the reported arrival of a key United Nations negotiator in Damascus, Syria, and an Iranian press dispatch saying that two Western captives, an American and a Briton, would be released soon.

The report in today’s editions of the Tehran Times said the releases would be made “on humanitarian grounds” and that the kidnapers would “most probably give priority to a British hostage.” It did not speculate on the timing.

The dispatch, picked up by international news agencies here, gave no source for the information, but the English-language Tehran daily, closely identified with Iranian President Hashemi Rafsanjani, has been generally accurate in past predictions of impending releases.

Only one Briton remains captive, churchman Terry Waite, 52, who was seized in January, 1987, as he was negotiating for the freedom of other hostages as the personal envoy of the Archbishop of Canterbury, head of the Anglican Church.

Four Americans are still in the hands of the militant pro-Iranian Lebanese kidnapers: journalist Terry A. Anderson, educators Thomas M. Sutherland and Alann Steen, and university official Joseph James Cicippio.

The newspaper report coincided with the arrival in Damascus of Giandomenico Picco, U.N. Secretary General Javier Perez de Cuellar’s representative in the stepped-up negotiations to resolve the hostage crisis. The Tehran Times said the Syrian capital was Picco’s first stop.

Putting his personal prestige behind the accelerated effort, Perez de Cuellar has helped win freedom for four Western hostages since August, most recently American professor Jesse Turner on Oct. 21.

But negotiations have been both delicate and difficult, involving the kidnapers, their political mentors in Lebanon and Iran, and the Israelis, whose release of captive Shiite Muslim militants has been instrumental in freeing the foreigners in Beirut.

The trade in captives involves hard bargaining, not simply the “humanitarian grounds” cited by the Tehran press report.

In the gritty business of swapping hostages, Waite and Anderson are considered to have the highest value and, according to many analysts, might not be released until the Israelis free their prize captive, Sheik Abdel Karim Obeid, a leader of the Lebanese Shiite Hezbollah movement.

Israeli officials have said that no more Lebanese prisoners will be freed until it gets further information on the fate of four remaining missing servicemen in Lebanon.

Perez de Cuellar’s initiative has been bolstered by Iranian President Rafsanjani’s steady campaign to improve Iranian relations with European countries despite the opposition of a powerful anti-Western clique in Tehran. The hard-liners, most notably former Interior Minister Ali Akbar Mohtashemi, retain strong influence with the Hezbollah movement.

The remaining Westerners listed as hostages include two Germans seized near the southern port of Sidon but believed to be captives of Palestinian elements, not Hezbollah, and an Italian businessman who disappeared in Beirut and has never been claimed as a captive by any of the militant groups.