The men may be trained and prepared to commit future suicide terrorist acts

US Attorney General John Ashcroft

The Americans have issued a worldwide alert and urged the public to help identify, locate and incapacitate the men.

Four of the suspected al-Qaeda operatives have been tentatively identified as: Abd Al-Rahim, Muhammad Sa'id Ali Hasan, Khalid Ibn Muhammad Al-Juhani and Ramzi Binalshibh.

The identity of a fifth individual is unknown.

Ramzi Binalshibh is alleged to have had connections with the ringleader of the hijackers

"These men could be anywhere in the world," Mr Ashcroft said.

He said the tapes were recovered from the rubble of a house in Afghanistan which belonged to Mohammad Atef, believed to have been Osama Bin Laden's military chief.

American officials say he was killed by a US air strike in November.

The US authorities have been unable to identify this man

Excerpts from the tapes show three of the men separately, two of them apparently making statements and one holding an automatic rifle.

Mr Ashcroft said little was know about the five suspects except for Ramzi Binalshibh, from Yemen.

The US authorities allege that he was a close associate of Mohammed Atta, the man believed to have been the ring-leader of the 19 hijackers who carried out the suicide attacks on 11 September.

Muhammad Sa'id Ali Hasan

In the indictment handed down in December against Zacarias Moussaoui, the only man yet charged in connection to the 11 September attacks on New York and Washington, Mr Binalshibh was named alongside the other hijackers as an unindicted co-conspirator.

FBI Director Robert Mueller said the tapes came from a "trove of valuable information" discovered in Afghanistan.

He said they were still being analysed to determine when they were made, adding that there was no evidence any of the suspects had entered the United States, although at least one had tried.