Net closing on terror plotters

US and European authorities are zeroing in on a small group of men in England, Germany and the United Arab Emirates believed to have plotted the September 11 attack and provided assistance to the hijackers, government officials said.

Some of the men are in custody, including an Algerian pilot that British prosecutors identified as the primary instructor for some of the hijackers.

The FBI found his name on a document in a car left by the hijackers at Dulles Airport outside Washington, one US official said.

Other suspected plotters remain at large and are the subject of an FBI-led manhunt, the officials told The Associated Press. Several belong to various groups loosely associated with Osama bin Laden’s al-Qaida network.

Among the groups are various cells of the Algerian-based Armed Islamic Group that joined forces with bin Laden, the officials said, speaking on condition of anonymity.

‘‘One should not focus on one individual, but focus one’s attention on a series of networks across the world,’’ FBI director Robert Mueller said.

One of those sought is a man in the United Arab Emirates who was sent a package from Mohamed Atta, the suspected leader of the hijacking teams, one official said.

The package contained money and documents and was mailed by Atta a few days before he hijacked a plane in Boston and flew it into the World Trade Centre in New York.

The information about the origins of the hijacking plot emerged as the US Justice Department announced that more than 480 people had been arrested or detained in the probe.

Investigators also released a four-page handwritten document left behind by the hijackers that included instructions on how to carry out their attack and Islamic religious references.

Evidence is growing that the plot was hatched, funded and assisted by several bin Laden sympathisers who gave instruction and support from Europe and the Middle East, officials told AP.

Much of the evidence about collaborators has emerged as the agencies have meticulously reconstructed the hijackers’ travels in the United States and Europe during their final months, and traced tens of thousands of dollars in financial transfers, officials said.

‘‘Part of our investigation, quite obviously, is trying to determine the past histories of each of the hijackers, trace their time in the United States, but also attempt to identify where they were prior to their coming to the United States and track their movements through any number of countries overseas,’’ Mueller said.

A law enforcement source said as the plot became more clear from the evidence, US authorities were learning the terrorists changed tactics from prior attacks.

The evidence indicates high-level plotters and planners avoided travelling to the United States where they might raise suspicions and instead funded and instructed the eventual hijackers from Europe and the Middle East, the official said.

Contacts the hijackers made in their final months in Germany, the United Arab Emirates, the Czech Republic and France have been one key in identifying potential backers, the officials said.