A British resident imprisoned in Guantanamo Bay has been charged over an alleged al-Qaeda plot to detonate a dirty bomb in apartment buildings in the United States.

Binyam Ahmed Mohamed, an Ethiopian national who came to Britain as a teenager, is accused by the Pentagon of plotting the attacks from secret training camps in Pakistan and Afghanistan.

Mr Mohamed, 29, is one of two British residents still held at Guantanamo despite requests for their release from the British Government. He is the twentieth inmate put forward to face a military tribunal, and the fifth in the past week.

His lawyers insisted yesterday that the evidence against him had been extracted under torture. They condemned the charges as part of a “rush to charge as many people as possible prior to President Bush leaving office”.

They filed a lawsuit in London last month in an attempt to force the British Government to hand over documents proving that the prisoner was tortured before being sent to Guantanamo.

Clive Stafford Smith, of the London-based human rights group Reprieve, said: “The least the British Government can do is insist that no British resident be charged in a kangaroo court on evidence tortured out of him with a razor blade.”

All the evidence against Mr Mohamed appeared to have been “derived from coercive interrogation and torture”, Mr Stafford Smith said in a letter to military prosecutors urging them to drop the case.

Mr Mohamed, an electrical engineer, was arrested in Pakistan in 2002 and taken to Morocco by the CIA. There, lawyers allege, he was tortured in order to extract a confession. Lawyers allege that his genitals were slashed with a scalpel and that he was repeatedly beaten.

Mr Mohamed is said to have conspired with Jose Padilla, an American citizen convicted by a federal court last year of conspiracy and material support for terrorism. Padilla, 37, was sentenced to 17 years in prison in January.

The Pentagon alleges that he and Padilla were instructed by Khalid Sheikh Mohammed, the self-confessed mastermind of 9/11, to rent apartments in large US cities, fill the corridors and air ducts with natural gas and a radioactive material and detonate the mixture. Mr Mohamed faces life imprisonment if convicted.

Khalid Sheikh Mohammed, the best known of all the Guantanamo inmates, is due to appear before a military tribunal in Guantanamo today, along with four other top suspects, including Mustafa Ahmed al-Hawsawi, the alleged financial executor of 9/11, and Ramzi Binalshibh, the alleged twentieth hijacker.

It will be Mr Mohammed's first public appearance since his dramatic arrest in 2003 when Pakistani police stormed the villa where he was hiding. They handed him over to the CIA, which held him in a series of secret overseas prisons for three years before sending him to Guantanamo. The revelation this year that he was subjected to harsh “coercive interrogation” techniques, including waterboarding, or simulated drowning, has also cast doubts over the veracity of his confession.

In a transcript of a confession released last year, Mr Mohammed claimed to have personally carried out or plotted most of the major Islamist terror attacks on the West over the past decade. In addition to the September 2001 plot, he claimed involvement in 30 other attacks and plots, including the bombing of the World Trade Centre in New York in 1993.

The US Military Commission Act rules out admitting evidence obtained under torture, presaging a lengthy debate at his trial over whether waterboarding constitutes torture. The US military is barred from employing the method but the CIA has clung firmly to its right to do so.

The five defendants all face the death penalty if convicted.

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