MABALACAT, Philippines

They stayed at a popular resort hotel here, drank whiskey with Philippine bargirls, dined at a restaurant that specializes in Middle Eastern cuisine and visited at least one of the local flight schools.

The two men suspected by the FBI of being at the controls of the planes that flew into New York's World Trade Center on Sept. 11 left those traces behind from visits from 1998 to 2000 to this hustling market town outside a former U.S. Air Force base, according to local residents who say they recognized the two from news photographs.

Philippine and U.S. investigators have been checking out the reported movements here of Marwan Al-Shehhi and Mohamed Atta. They would not confirm the accused hijackers' presence in the Philippines, but the local hotel workers were willing to discuss them.

Mr. Al-Shehhi, whom the FBI has identified as the pilot of United Airlines Flight 175 when it slammed into the trade center's south tower, threw a party with six or seven Arab friends at the Woodland Park Resort Hotel here in December, said a former waitress at the hotel, Gina Marcelo. "There were about seven people," she said. "They rented the open area by the swimming pool for 1,000 pesos. They drank Johnnie Walker Black Label whiskey and mineral water. They barbecued shrimp and onions. They came in big vehicles, and they had a lot of money. They all had girlfriends." She cited "one big mistake they made." Unlike most foreign visitors, "They never tipped," she said. "If they did, I would not remember them so well."

Victoria Brocoy, a chambermaid at the Woodland, recalls Mr. Atta, the Egyptian who investigators believe flew American Airlines Flight 11 into the trade center's north tower. "He was not friendly. If you say hello to him, he doesn't answer. If he asks for a towel, you do not enter his room. He takes it at the door."

Mr. Atta was by no means a recluse. "Many times I saw him let a girl go at the gate in the morning," she said. "It was always a different girl." .:The accounts here tend to confirm reports from the United States that at least some of the accused hijackers had free-wheeling lifestyles full of sex and alcohol, and took precautions to keep their identities secret.

They are assumed to have gravitated here in search of flying lessons. The area is a hub for pilots and flying instructors, Filipinos as well as foreigners, as a result of its relationship to Clark Air Base, converted to a special economic zone after the withdrawal of U.S. forces in 1991. At least two flying schools offer lessons, one of them in the zone; the other, the Angeles City Flying Club, is owned by the same corporation as the Woodland hotel, about 20 kilometers to the east.

The hijacking suspects were introduced to the hotel, according to workers who saw them, by a Jordanian businessman who runs a travel agency in Manila and often stays there but denies having known them. .Their presence aroused little curiosity in the male-dominated foreign community that ranges from retired military people to tourists from Europe, Australia and the Middle East, many of them drawn by the cheap prices and the availability of the local women.

The investigation by Philippine and American authorities has focused not only on the timing of their visits to this town about 100 kilometers (60 miles) north of Manila but also into exactly what they were doing and why.

The search is complicated by the fact that they made certain not to register under their own names, but two patterns have emerged from the investigation, according to Philippine police officials. The first is that the two displayed a keen interest in learning how to fly small planes, and the second is that they dominated a clique of Arab visitors, most of whom have not been seen since shortly before the attacks.

Ferdinand Abad, who was working as a security guard at the entrance to the hotel in mid-1999, remembers Mr. Atta asking at what time he should wait outside the Woodland hotel for a van to take him to the Angeles City Flying Club.

"I told him about 7 in the morning, and he gave me a tip of 50 pesos," - about $1 - Mr. Abad said. "Two or three times a week the van would pick him up. He didn't say he was going to fly. After our first meeting, he never talked, never said hello."

The driver of the van, Mr. Abad said, was Melvin Troth, manager of the flying club, who retired as a master sergeant in the U.S. Air Force in 1986 after serving his last tour at nearby Clark Air Base. Mr. Troth told investigators, however, that the names of Mr. Atta and Mr. Al-Shehhi did not appear in his records. ."I pick up a lot of people and take them out here," he protested to a colonel from the Philippine National Police headquarters, one of a stream of official visitors to the Flying Club in recent days, as a reporter was present. "It's a regular procedure. I don't remember them."

On the base, converted to a special economic zone after the Philippine Senate refused to extend the bases agreement with the United States in 1991, Philippine officials respond to such denials with derision mingled with serious concern.

"We want the whole world to know about the danger of these people around here," said Tony Salenga, chief executive assistant to the chairman of the Clark Development Corp., which is responsible for attracting investors to the former base to set up stores and factories there. "We believe they were establishing cells right here."

Residents recall that friends of Mr. Atta and Mr. Al-Shehhi often gathered at the Woodland Park and at the Jerusalem Restaurant in Angeles City, which borders the base just south of here.

Trudis Dago, manager of the restaurant, remembered Mr. Atta as someone who "would never smile and would never talk to anyone except his friends." ."I knew this face when I saw it in the paper," she said.