By Steve Swann
Home affairs reporter
Secret telegram: Obtained by the BBC
The BBC has obtained a copy of a telegram believed to have been cabled from MI5 headquarters to the official it sent to Pakistan to question the terrorist suspect Binyam Mohamed.
Almost all of the 35-page document has been completely redacted but details are published of the suggested questions to be asked.
It was dated from May 2002 - two days before the interview was conducted by an official known in legal proceedings as "witness B."
Mr Mohamed, an Ethiopian national who had been living in London, was arrested in Karachi in April 2002 trying to leave the country on a false passport.
The US authorities initially accused him of having attended terrorist training camps and planning to travel to the US to set off a radiological device.
Mr Mohamed claims he was brutally tortured in Morocco
But the allegations against him were eventually dropped and he returned to the UK earlier this year.
Mr Mohamed claims the British authorities colluded in his mistreatment during his detention in Pakistan and his subsequent rendition to Morocco, where he says he was brutally tortured before being held in custody in Afghanistan and Guantanamo Bay.
The British government denies condoning, authorising or co-operating in torture.
Witness B was sent to Pakistan after MI5 obtained permission from the US to question Mr Mohamed.
At a High Court hearing last year he denied that he had put Mr Mohamed under pressure to co-operate or made veiled threats to him.
An earlier report from the Intelligence and Security Committee concluded "the interview was conducted by an experienced officer and was in line with the Service's guidance to staff on contact with detainees".
Nevertheless, the committee is looking into the case again and the Metropolitan Police is investigating whether to press charges against British officials.
In the telegram, MI5 refers to Mr Mohamed as the "dirty bomber" and states that he is a "committed Islamist".
It wants to know about his time in the UK, which mosques he used and who he associated with there.
The telegram states: "Has he ever attended training camps in the UK? If so where did he train, with who, what was he taught?"
It also suggests Mr Mohamed is questioned about his passport and his travel arrangements to Pakistan.
The document said: "Who did he buy the passport from? How did he make contact with this individual? Where did this individual live, did he visit him at home or did they meet him in a neutral location?"
The MI5 document describes Mr Mohamed as a "committed Islamist"
There is also a proposed section of questioning about Fouad Zouaoui, the name said to have been used on the false passport held by Mr Mohamed. It states: "Which mosques does he attend? Is he involved in any form of radical Islam?"
Of his time in Pakistan, it suggests Mohamed is asked who met him when he arrived and whether he stayed with any other people from Britain.
On the alleged plot to bomb the US, he should be asked what websites "were studied in preparing the plans for the dirty bomb?"
Mr Mohamed was originally said to have conspired with Jose Padilla, a US convert to Islam, but the charges against Padilla were dropped, although a US court convicted him of other terrorist offences.
On Tuesday at the High Court, lawyers for Foreign Secretary David Miliband argued that disclosing a seven-paragraph summary of Mr Mohamed's alleged mistreatment in Pakistan would damage national security.
It would also damage Britain's ability to share future intelligence secrets with the US, the court heard. The panel of two senior judges is expected to rule on that in the coming weeks.