'Fifty' suspects in FBI investigation

German police raided a Hamburg flat on an FBI tip-off

The FBI says the identities of many of those involved in the terror attacks on America are known.

US Attorney General John Ashcroft said on Thursday that there were at least 18 hijackers, armed with knives, on the four planes.

There have been unconfirmed reports that rescue teams have found the body of one of the terrorists involved in the attacks - and the body of an air stewardess with her hands tied behind her back.

Progress of the investigation so far:

• Black box retrieved from wreckage of hijacked airliner in Pennsylvania and signal received from black box of plane that crashed at the Pentagon.
• Mr Ashcroft says the FBI is working on "thousands and thousands" of leads.
• 2,055 tip off calls to FBI hot line and over 22,000 tips sent to special web-site.
• About 7,000 FBI agents in biggest manhunt in US history
• The FBI says it has identified as many as 50 people involved in "well financed" operation. Some were trained as pilots in the US
• German police arrest man in Hamburg
• Two suspects linked to Hamburg flats
• FBI quiz man in Florida, say reports
• Mexico border authorities on alert
• Two Boston hotels raided.

About 7,000 agents involved in the biggest manhunt in American history are searching for as many as 50 others reported to have helped execute the plan.

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German police, acting on an FBI tip-off, arrested a man on Thursday after a raid on a Hamburg flat where two of the suspected terrorists are believed to have lived.

'Pilot' quizzed

The suspects, Mohamed Atta, 33, and Marwan Al-Shehhi, 23, were each on one of the two planes which smashed into the World Trade Center, said Hamburg security officials.

It is thought they were trained for their devastating mission at a flying school in Florida.

According to German records, both men are from the United Arab Emirates.

German prosecutors said they were investigating a Hamburg-based terrorist network formed "to attack the United States in a spectacular way through the destruction of symbolic buildings".

CNN reported that another suspect arrested in Florida is helping the FBI.

Adnan Bakhari, described as a Saudi pilot, was arrested on Wednesday, after police seized a rented car in Maine.

Mexico alert

Mohamed Atta: Suspect

Officials at Ciudad Juarez airport close to Mexico's border with the United States said that US authorities have asked them to look out for six people suspected of involvement.

Three of the six are said to hold Pakistani passports.

Airport security chief, Juan Carlos Martinez, said he believed that the US authorities had given similar information to other Mexican airports along the 2,000km border with the United States.

Law enforcement agents also searched homes and businesses in Florida in connection with the attacks, focusing on the Huffman Aviation School where two suspects may have received flight training.

In Boston, a car believed to belong to the hijackers was confiscated. Officials said it contained an Arabic-language flight manual.

Thailand search

Investigators also raided two hotels near Boston thought to have been used by the hijackers. In one room a link was found to a name on one of the flight passenger lists.

In Thailand, security police said they were on the lookout for 15 Arab men wanted by the CIA in connection with Tuesday's devastation.

Mr Mueller said the bureau had established command posts at the places of origin and destination of the flights, where the investigation was being assisted by:

• 4,000 special agents
• 3,000 support personnel
• More than 400 laboratory personnel.

One group of hijackers is believed to have crossed from Canada and to have had ties to Mr Bin Laden.

The FBI is dealing with 700 leads from the public and has set up a website containing a form people can use to report any new information on the attacks.

US Attorney General John Ashcroft also said the government had "credible evidence" that both the White House and the presidential jet, Air Force One, had been targeted in the attacks.

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