The leader of an alleged British al Qaida terror cell wanted a transport worker to carry out a suicide bombing mission, the Old Bailey heard.

Omar Khyam, from Crawley, singled out a man called Imran who worked for London Underground to blow himself up with a belt bomb, according to supergrass Mohammed Babar.

But when Babar asked Imran to do the suicide mission on behalf of Khyam, he turned it down, said Babar.

Babar said Imran had been at a training camp in Pakistan with other Britons in the summer of 2003. Khyam, Babar and others had had gone to another part of the mountain in Malakand to test a bomb - and had filmed themselves doing it.

They returned from the terror camp without Imran, who followed later.

Babar said: "Ausman (Khyam) was going to use him for the operation in the UK and he wanted to know if Imran would be willing to do it. He wanted to do a martyrdom operation using a belt bomb and he had Imran in mind."

Asked by David Waters QC, prosecuting: "Is that a suicide bomb?" Babar replied: "Yes".

Babar said he approached Imran on behalf of Ausman when he returned from the mountain.

He said: "Time had lapsed and when he came down, I asked Imran if he wanted to do it and he said no because he thought these guys would never carry it out."

The court was told last week that Imran worked for London Underground, had bad knees and walked with a limp following an accident.

American Babar, 31, has been given immunity from prosecution to testify aganist seven British citizens who deny conspiring with a Canadian to cause explosions in Britain.

Omar Khyam, 24, his brother Shujah Mahmood, 19, Waheed Mahmood, 34, and Jawad Akbar, 22, all from Crawley, Salahuddin Amin, 31, from Luton, Beds, Anthony Garcia, 23, of Ilford, east London, and Nabeel Hussain, 20, of Horley near Gatwick, deny the charge.

Khyam, Garcia and Hussain also deny a charge under the Terrorism Act of possessing 600kg (1,300lb) of ammonium nitrate fertiliser for terrorism.

Khyam and Shujah Mahmood further deny possessing aluminium powder for terrorism.

It is alleged they talked of bombing the Bluewater shopping centre in Kent, a large London nightclub and trains in addition to poisoning football fans with spiked beer.

Babar alleged yesterday that the cell planned to smuggle the ingredients for a bomb into the UK using shampoo bottles, shaving cream and bags of dried fruit.

They also bought a small cassette recorder in which to conceal the detonators, he said.

He said he and Khyam discussed hiding ammonium nitrate in bags of almonds, raisins or dried apricots.

These would then be sent to the UK in a parcel via the delivery company Federal Express, the court heard. Khyam had claimed to have been given orders by Abdul Hadi, who the court had earlier heard described as the number three figure in al Qaida.

The orders were for no one to pray in public and to dress as Western tourists as some of them made their way to the training camp, said Babar.

The trial was adjourned to today.