Reprieve director Clive Stafford Smith has written to the judge appointed to preside over the forthcoming inquiry into UK complicity in torture, seeking his recusal on the basis that he has already completed a secret inquiry, and accordingly would be more properly cited as a witness in the inquiry, rather than its chair.

In a letter copied to the Prime Minister, Stafford Smith says Sir Peter Gibson's impartiality is fatally compromised.

"Welcome though the Torture Inquiry is, the current structure is a sham," Stafford Smith says.

"Sir Peter Gibson was perhaps the least appropriate judge to evaluate the Security Services. The government must get serious about learning the mistakes of the past, rather than try to cover them up, or we are in for a long, hot summer.”

Reprieve said that as the Intelligence Services Commissioner, it has been Sir Peter’s job for more than four years to oversee the Security Services, and accordingly say he cannot now be the judge whether his own work was effective.

"David Miliband has stated publicly that Sir Peter has already conducted a secret inquiry, at the previous government’s request, into allegations of misconduct. Yet because it is secret, none of us may know what his conclusions were," Repreive said in a statement.

"Sir Peter has – in each of his three annual reports – opined that all members of the Security Services are “trustworthy, conscientious and dependable”, thereby entirely prejudging the issues before the inquiry. Contrast this to the criticisms levelled by Lord Neuberger, the Master of the Rolls, in the case of Binyam Mohamed.

"Part of Sir Peter’s job, as ISC, was to oversee ministerial authorizations that would allow the Security Services to violate the law abroad, including sanctioning British involvement in abusive interrogations. Since evidence will be presented that such interrogations have continued during Sir Peter’s tenure, he either validated these actions, or he has been hoodwinked as ISC. Either way, he should be a witness at the inquiry."