Hunt Launched for 20 Tied to Bomb Suspect : Terrorism: They are said to be the core of Yousef’s cell in Philippines. Concern over follow-up attacks is cited.

An international manhunt has been launched to track down 20 Muslim extremists--15 of various Asian and Middle East nationalities and 5 Filipinos--linked to Ramzi Ahmed Yousef’s alleged terrorist operations in the Philippines, according to Philippine and U.S. officials.

The extremists are widely believed to make up the core of a cell operated by Yousef, who was arrested last week in Islamabad, Pakistan, for allegedly masterminding the 1993 bombing of the World Trade Center in Manhattan. The cell is thought to have plotted to attack Pope John Paul II and U.S. planes flying Asian routes. The extremists may be planning to follow through on those attacks or others, according to Asian and American sources.

Philippine authorities revealed Monday that evidence Yousef left behind also indicated plans to bomb U.S. diplomatic facilities in Asia, many of which are now on heightened alert.

The new and broader evidence accumulated in both Manila and Islamabad is expected to lead to new charges in addition to the 11 counts Yousef faces for the World Trade Center bombing, U.S. officials said.

But the extent of the new charges for plotting against other American diplomatic and commercial interests is unclear. Law enforcement officials said they were still sorting through leads.

New evidence in Manila, for example, shows that the Dec. 11 bombing aboard Philippine Airlines Flight 434, allegedly masterminded by Yousef, was “a test run for planned bombings of U.S. commercial aircraft” in Asia, Philippine officials said.

The test involved the logistics of getting a bomb into Manila’s international airport and then on a plane. The explosives on Flight 434 were small. One man was killed and 10 injured.

The new charges, however, may not alter Yousef’s fate. He already faces 240 years in prison if convicted of the same World Trade Center charges on which four others were convicted for the most serious domestic terrorist attack in U.S. history.

But Yousef’s capture may not end the trail of terror.

U.S. officials now fear that rather than force the extremists to abandon their schemes, Yousef’s arrest may instead lead his cell to carry on with the planned attacks in retaliation or in an attempt to win his release, the sources added.

Although the prime focus of the manhunt is in the Philippines, U.S. intelligence and law enforcement agencies, Interpol and other Asian and Middle East governments are involved in the search.

The group of 20 extremists “conducted unusually regimented activities in a secluded beach area in Lian Batangas,” a province south of Manila, a Philippine spokesman said. He would not elaborate. The cell is the third Yousef is widely believed to have built.

Yousef fled the Philippines days before the intended papal attack after his apartment was raided by security forces. A small fire in the apartment in Malade, forced police to move in before they had intended, officials said. They had hoped to have more time to trace other operatives. Afterward, apartment block residents identified the occupant, who carried documents under the name Naji Owaidah Haddad, from photographs as Yousef.

U.S. officials now believe he is a Pakistani who was born in Kuwait. His family comes from Baluchistan, a coastal region abutting Iran, which has its own large Baluchi population. But Yousef has roamed the world under many nationalities and aliases. He entered the United States in 1992 on an Iraqi passport. In Manila, he claimed to be Moroccan, while he entered Pakistan last week from Thailand on a Pakistani passport with yet a third name, Ali Mohammed.

U.S. authorities are also looking more deeply into Yousef’s wide-ranging links, which stretch from New York to the Far East, through Istiaq Parker, a South African Muslim who lived across the street from the guest house where Yousef was apprehended in Islamabad last week.

Parker, his wife and child have been brought to the United States under the witness protection program, U.S. officials have confirmed. Parker has been variously described as a disaffected member of Yousef’s cell in Pakistan and an acquaintance who turned informant for the $2-million reward.

In an undisclosed place, Parker is talking with U.S. authorities about other terrorist activities in which Yousef may have been involved as well as Yousef’s contacts, sources of funding, training and techniques, U.S. sources said.

The Pakistani News reported Monday that Parker had known Yousef since 1992.

Parker attended Islamabad University, which has a large community of Muslim foreign students. Yet acquaintances painted a picture of him as a loner with business ambitions. He did not fraternize with other South African Muslims in Pakistan.

His wife, Fehmida, was “disillusioned and wanted to go back to South Africa. She didn’t like the living conditions in Pakistan,” according to a Parker friend.

Parker lived above a video store from which ironically he had recently rented “Trial by Jury” and “Blown Away,” the latter a thriller starring Tommy Lee Jones as a vengeful and murderous bomber.

Times staff writers Ronald J. Ostrow in Washington and John-Thor Dahlburg in New Delhi contributed to this story.