A man was arrested in New York in connection with this week's four hijackings, marking the first big break in a global investigation to find those responsible for the world's worst terrorist atrocity.
US Federal authorities took the man into custody on a material witness warrant, said Jim Margolin, spokesman for the FBI in New York. The warrant allows authorities to hold someone considered crucial to the investigation without charging him with any crime. The man's identity was withheld.
A law enforcement source said the man arrested was the same person detained on Thursday at John F. Kennedy Airport after showing what authorities said was a pilot's license issued to his brother.
Both Mr Margolin and New York Police Commissioner Bernard Kerik refused to provide any further details on the arrest. Court records were sealed.
Pilot training is a central theme of the huge investigation into Tuesday's attacks. Several of the 19 hijackers whose names were released by the FBI on Friday were pilots and had trained at aviation schools in Florida.
Among the 19 was Mohamed Atta of Hollywood and Coral Springs, Florida, identified by German authorities as being linked to an Islamic fundamentalist group that planned attacks on American targets.
Atta received pilot training at Huffman Aviation in Venice, Florida, and took two three-hour courses at SimCenter Inc. in Opa Locka, Florida, where he trained on a Boeing 727 full-motion flight simulator.
Besides Atta, the hijackers who were believed to be pilots included Hani Hajour, who was on the flight that crashed into the Pentagon; Wail Alshehri and Abdulaziz Alomari, who were on one of the Boston flights; Marwan Al-Shehhi, hijacking on United Flight 175 out of Boston and Ziad Jarrahi, who flew on United Flight 93 out of Newark, New Jersey, which crashed in a field 80 miles (130 kilometers) from Pittsburgh.
"The fact that there were a number of individuals that happened to have received training at flight schools here is news, quite obviously," said FBI Director Robert Mueller.
"If we had understood that to be the case, we would have, perhaps one could have, averted this," he said.
In another development, two men detained at an Amtrak station in Fort Worth, Texas, were interviewed by FBI agents, taken into custody and then flown to New York, officials said Friday.
They were removed from an Amtrak train during a routine drug search Wednesday night. Although no drugs were found, the men had box-cutting knives, authorities said, and also carried about dlrs 5,000 in cash, according to a federal official who spoke on condition of anonymity.
Hijackers in Tuesday's attacks used knives and box cutters to take control of the airliners.
FBI agents fanned out across the country interviewing people about the 19 hijackers and gave local police departments and federal law enforcement agencies a list of 100 people whom agents want to question in the attacks.
"We believe they may have information that could be helpful to the investigation," said Attorney General John Ashcroft.
The FBI dispatched teams of agents to airports, where authorities were checking passenger manifests against the list of 100 people.
Authorities also were looking for a Muslim cleric who previously was questioned by prosecutors in the 1998 embassy bombings case linked to Osama bin Laden, a Saudi extremist suspected of sponsoring a worldwide terrorist network.
The cleric, Moataz Al-Hallak, left the north-east on Monday, the day before the attacks, and travelled to Texas, according to authorities and his lawyer.
Hundreds of subpoenas have been issued in the search for those who assisted the hijackers. More than 30 search warrants have been executed and investigators have seized computers and other documents.
A number of people who were questioned as part of the investigation have been arrested because of problems with their immigration status. None has been charged, but officials declined to say whether they have been cleared.Reuse content