15 FBI suspects are Saudi pilots

Fifteen people the FBI wants to interview as it investigates last week's terror attacks are pilots with Saudi Arabian addresses, it was reported today.

Nine of the 15, who are part of a 220–strong "watch list" issued by the agency, are pilots for Saudia, the country's national airline, USA Today reported.

The list includes a total of 37 registered pilots, five of whom are students, and 12 aircraft mechanics, all of whom are believed to be in America.

The list, which continues to grow, has so far resulted in 115 people being detained, most of them on immigration charges.

Four are known to have been arrested as "material witnesses", meaning investigators believe they have information about the hijackings.

The list includes people known or suspected to have been associates of the 19 hijackers, all of whom lived at some point in different parts of America.

The authorities today issued closed circuit television pictures of two men passing through Boston airport before they hijackled an American Airlines plane and crashed it into New York's World Trade Centre.

And today it emerged the FBI had obtained e–mails between the hijackers and their associates.

Specialist agents found hundreds of e–mail messages sent between the 19 and other people, some of them as much as 45 days before the attacks last Tuesday.

The e–mail messages include both evidence and casual chat in both English and Arabic, an FBI official told ABC News.

"They used the Internet and they used it well," he said.

To cover their tracks, the hijackers used both their own computers and those in public libraries to send e–mail, while the FBI has seized computers from many of those on their watch list detained in the last week.

The moves in the investigation came as it emerged some of the hijackers may have used other people's identities in the run–up to the attacks.

A London–based Arabic newspaper, Asharq al–Aswat, reported a Saudi Arabian citizen who had his passport stolen after his apartment in Denver, Colorado was burgled in 1995, was one of the victims of identity theft.

Abdulaziz Alomari was one of the names on the list, but today he told the newspaper: "The name is my name, and the birthdate is the same as mine, but I am not the one who bombed the World Trade Centre in New York."

Some may even have stolen the identities of legitimate pilots, pointing to years of planning in the run–up to the hijackings.

Three men arrested in Detroit are being investigated as possibly holding the key to the identity thefts.

Ahmed Hanna, 33, Karim Koubriti, 23, and Farouk Ali–Hainmoud, 21, were found in an apartment registered to another man on the watch list in possession of a false immigration admission form, visa and immigrant identification card.

They have been charged with criminal violations of immigration law and when they were arrested computer files, documents in Arabic and a day planner with references to an "American base in Turkey" and "the America foreign minister" were seized.

Authorities are understood to want to question them about a thwarted terrorist attack on the America air force base in Incirlik, Turkey.

The base is where American planes maintaining the no–fly zone over Northern Iraq are based.

The men will appear in court on Friday, the first time anyone detained in connection with the attacks has made a court appearance.

Another man being held as a material witness is suspected to have detailed information about how at least one of the hijackers was financed.

Dr Al–Bader Al–Hazmi, a 34–year–old Saudi Arabian radiologist working in San Antonio, Texas, was detained in the town and flown to New York for questioning, where he could appear for questioning in front of the grand jury investigating the attacks.