Barack Obama, the US president, has previously dismissed calls for such a commission, saying he is more interested in "looking forward than I am in looking backwards", although he has stressed that "nobody is above the law".

In depth
The move comes a day after the US justice department released memos from the Bush era which would have granted sweeping powers to authorities following the September 11 attacks in 2001, including the ability to conduct raids in the US without a warrant.

'Public approval'

In February Leahy told the New York Times that he envisaged the commission as not being formed by members of congress but by an outside group of people "universally recommended as fair-minded".

He also told the paper he felt the commission should have the power to subpoena witnesses and possibly grant immunity for officials who testify truthfully, in a similar mould to South Africa's post-apartheid Truth and Reconciliation Commission.

A USA Today/Gallup poll conducted earlier in February found that 62 per cent of US citizens favour either a criminal investigation or an independent panel to look into allegations of torture.

'Zero-sum' battle

On Monday the Obama administration released nine legal opinions showing that after the September 11 attacks the Bush administration appeared to have deemed certain rights guaranteed under the US constitution to not apply in the so-called war on terror.

The memos included assertions that the US president had broad power to detain US citizens suspected of terrorism and to suspend treaty obligations on issues as the president saw fit.

The Bush administration ultimately abandoned many of the legal conclusions, but the documents themselves had been withheld from the US public.

"Too often over the past decade, the fight against terrorism has been viewed as a zero-sum battle with our civil liberties," Eric Holder, the US attorney general, said in a speech before the documents were released.

"Not only is that school of thought misguided, I fear that in actuality it does more harm than good."

Also on Monday, the Central Intelligence Agency (CIA) said it had destroyed 92 tapes of interrogations of "terror" suspects, far more than previously acknowledged.

Obama has rolled back some of the Bush-era national security policies, including the decision to close the US prison camp at Guantanamo Bay in Cuba.