Secret documents show former PM was warned of torture of Britons just weeks after US began arresting terror suspects

Tony Blair was warned a matter of weeks after American forces began rounding up terror suspects that British nationals held by the US in Afghanistan and Guantánamo Bay were being tortured, secret documents disclosed in the high court reveal.

He expressed concern about their treatment after initially being sceptical, he admits in a hand-written note on a Foreign Office (FO) document dated 18 January 2002. It appears among heavily redacted MI5 and FO documents released in court hearings in which British nationals are suing the government, MI5 and MI6.

The partly redacted FO note refers to a visit to Guantánamo Bay by the International Committee of the Red Cross (ICRC). "There will be intense press interest in any conclusions they reach on humanitarian issues," it says, adding that the ICRC was unlikely to make its views public.

An official adds: "This will continue to be a difficult issue to handle, both in procedural and legal terms with the US and in handling parliament and the media here."

Under the official's comment, Blair writes: "The key is to find out how they are being treated. Though I was initially sceptical about claims of torture, we must make it clear to the US that any such action would be totally unacceptable and v quickly establish that it isn't happening."

Evidence has since emerged that the British government knew the US was mistreating and torturing UK nationals and residents after January 2002 and for years afterwards, but did not seriously protest about it.

Evidence, notably in the case of Binyam Mohamed, an Ethiopian-born British resident, shows that MI5 co-operated with the CIA, which was active in mistreatment and torture.

A separate, previously classified Ministry of Defence document now released in heavily redacted form and dated 13 January 2002, warns that "the US treatment of the prisoners could be judged to be... [phrase blacked out]".

After noting that the ICRC was denied access, the writer of the note continues: "It is clear that the US is pushed logistically but my understanding of the Geneva Convention is that this is no excuse".

The high court heard today that MI5 and MI6 were continuing to refuse to reveal information about when they were told the US had captured and imprisoned UK nationals and residents before flying them to the Guantánamo Bay prison in Cuba.

The case is being brought by Mohamed, Bisher al Rawi, Jamil el Banna, Richard Belmar, Omar Deghayes, and Martin Mubanga against MI5, MI6, the attorney general, the FO and the Home Office.

In one document, an official at the British embassy in Washington warns the FO in London reported back on discussions with the US in October 2001 about detention and treatment of detainees. "I drew attention to ECHR Article 3 [the European human rights convention's ban on torture and inhuman or degrading treatment] ..."

In January 2002 an MoD official noted: "From my visit to Bagram [prison in Afghanistan] and watching the reception of the 80 plus prisoners, it would seem that this detainee issue is one that has the potential to reflect badly on the US/coalition ... the US treatment of the prisoners could be judged to be [redacted]".

Another document, a 19-page appendix to a cabinet briefing paper dated 14 January 2002 and headed "UK nationals held in Afghanistan" is completely redacted.

During the court hearings, Jonathan Crow QC, for the security and intelligence agencies, said it was difficult and time-consuming for MI5 and MI6 to collate the documents relating to the case. Mr Justice Silber intervened at one point, saying: "But it is important in a case of this magnitude".

Richard Hermer QC, for the former detainees, told the court that at the heart of the case was the question of when MI5 and MI6 first became aware of the prisoners' treatment by the US. They were "pretty straightforward questions", he said.