Another of the men named by the FBI as a hijacker in the suicide attacks on Washington and New York has turned up alive and well.

The identities of four of the 19 suspects accused of having carried out the attacks are now in doubt.

Saudi Arabian pilot Waleed Al Shehri was one of five men that the FBI said had deliberately crashed American Airlines flight 11 into the World Trade Centre on 11 September.

His photograph was released, and has since appeared in newspapers and on television around the world.

Hijacking suspects

Flight 175: Marwan Al-Shehhi, Fayez Ahmed, Mohald Alshehri, Hamza Alghamdi and Ahmed Alghamdi Flight 11: Waleed M Alshehri, Wail Alshehri, Mohamed Atta, Abdulaziz Alomari and Satam Al Suqami Flight 77: Khalid Al-Midhar, Majed Moqed, Nawaq Alhamzi, Salem Alhamzi and Hani Hanjour Flight 93: Ahmed Alhaznawi, Ahmed Alnami, Ziad Jarrahi and Saeed Alghamdi

Now he is protesting his innocence from Casablanca, Morocco.

He told journalists there that he had nothing to do with the attacks on New York and Washington, and had been in Morocco when they happened. He has contacted both the Saudi and American authorities, according to Saudi press reports.

He acknowledges that he attended flight training school at Daytona Beach in the United States, and is indeed the same Waleed Al Shehri to whom the FBI has been referring.

But, he says, he left the United States in September last year, became a pilot with Saudi Arabian airlines and is currently on a further training course in Morocco.

Mistaken identity

Abdulaziz Al Omari, another of the Flight 11 hijack suspects, has also been quoted in Arab news reports.

Abdelaziz Al Omari 'lost his passport in Denver'

He says he is an engineer with Saudi Telecoms, and that he lost his passport while studying in Denver.

Another man with exactly the same name surfaced on the pages of the English-language Arab News.

The second Abdulaziz Al Omari is a pilot for Saudi Arabian Airlines, the report says.

Meanwhile, Asharq Al Awsat newspaper, a London-based Arabic daily, says it has interviewed Saeed Alghamdi.

Khalid Al-Midhar may also be alive

He was listed by the FBI as a hijacker in the United flight that crashed in Pennsylvania.

And there are suggestions that another suspect, Khalid Al Midhar, may also be alive.

FBI Director Robert Mueller acknowledged on Thursday that the identity of several of the suicide hijackers is in doubt.

(Note: An update on this story was published in October 2006 in the BBC News editors' blog)