Image caption Saajid Badat has refused to travel to the trial because he fears arrest in the US

A British man convicted of plotting to blow up an aircraft has told a court that Osama Bin Laden said his attack would bring down the US economy.

Saajid Badat said he had intended to kill hundreds of passengers by detonating a device hidden in his shoe - but he pulled out at the last minute.

His recorded testimony was played at the New York trial of Adis Medunjanin.

In exchange for co-operating with prosecutors, Badat was released two years early from his 13-year jail term.

Details have also emerged of how Badat was radicalised by Babar Ahmad, a British terrorist suspect who has been held for over seven years awaiting extradition to the US on terrorism charges.

Fascinating details

Badat's evidence was recorded more than a week ago in the UK, and played in the Brooklyn courtroom on Monday.

Released from jail in 2010, he refused to travel to the trial because he feared arrest in the US for his role in the shoe-bombing campaign al-Qaeda had planned as a follow-up to 9/11.

BBC home affairs reporter Steve Swann said Badat provided fascinating details about the inner workings of Bin Laden's terrorist group.

Badat, a 33-year-old former grammar school student from Gloucester, said he had drawn a salary from the group during two years in Afghanistan in the late 1990s.

He explained how he had risen up the ranks to teach a course in using explosives, although he said it was unlikely that any of his students went on to carry out bomb attacks.

Badat said he was summoned shortly after 9/11 by al-Qaeda's leaders, who "asked me to take an explosive device on board an airplane and then detonate it".

In a one-to-one meeting with Bin Laden, he was told the justification for the mission.

Changed mind

The al-Qaeda leader told Badat that "the American economy is like a chain", he said.

"If you break one link of the chain, the whole economy will be brought down.

Image caption Adis Medunjanin is accused of plotting an attack on the New York subway system

"So after the 11 September attacks, this operation will ruin the aviation industry and in turn the whole economy will come down."

Badat said his final orders were given by Khalid Sheikh Mohammed, the man who has admitted masterminding the 11 September attacks and who is being held at Guantanamo Bay where he will be tried by a military tribunal.

The court heard that Badat had agreed to kill himself and everyone on the plane, but changed his mind when he got back to the UK.

But he admitted he kept the bomb parts hidden under a bed because "whilst I had not undertaken the mission, the al-Qaeda ideology I had not abandoned so that principle of remaining armed stayed with me".

Badat wrote an email to his handler: "You'll have to tell van Damm he could be on his own."

Fellow plotter Richard Reid - aka van Damm - failed in his attempt to blow up a plane with his shoe. The investigative trail led to Badat, who was arrested and jailed in 2005.

Badat explained how, after leaving home as a teenager, he was first introduced to radical Islam in south London.

He was befriended by Babar Ahmad, who is accused of using the internet to support terror groups.

The jury heard how Mr Ahmad arranged for Badat to receive "training in taking up arms", and that "when we talk about jihad it meant armed jihad, taking up arms".

In an exclusive prison interview earlier this month with BBC News, Mr Ahmad denied he was a terrorist.

But the European Court of Human Rights has ruled that he can be extradited to the US to stand trial on terrorism charges.

TV screens

Adis Medunjanin, a Bosnian-born US citizen, denies involvement in a suicide bomb plot on the New York subway in 2009.

Badat's 2.5-hour testimony, for which he was wearing a smart grey suit with a bright blue tie, and had his head shaved completely bald, was played on a series of TV screens in the Eastern District Court.

The BBC's Laura Trevelyan, in the court, said the room was silent as the softly-spoken Badat gave details of his meetings with Bin Laden and Khalid Sheikh Mohammed.

Hearing in 2008 that Khalid Sheikh Mohammed was facing trial for the 9/11 attacks, Badat decided to give evidence against him.

In return for agreeing to testify against al-Qaeda leaders, Badat signed a new co-operation agreement in in 2009.

The benefits Badat received for turning supergrass included parole, housing, phone and internet access, unemployment benefit and courses to help him return to society.

Today he has a job, and obligations to help UK and US prosecutors.

It is the first time a convicted UK terrorist has entered into an agreement with the Crown Prosecution Service (CPS) to give evidence in a trial against other alleged terrorists.

Prosecutors earlier said Badat's "main motivation" in helping had been to prove he had renounced terrorism with actions as well as words.

He saw himself and others like him as victims manipulated and exploited by Bin Laden and Khalid Sheikh Mohammed, they said.