http://news.bbc.co.uk/2/hi/americas/4175713.stm

The former head of the US Department of Homeland Security has said torture may be used in certain cases in order to prevent a major loss of life.

Speaking to the BBC, Tom Ridge said the US did not condone the use of torture to extract information from terrorists.

But he said that "under an extreme set of circumstances" such as the threat of a nuclear attack, "it could happen".

It comes a day after the US was accused of eroding human rights by campaigners.

Prisoners shackled

A report by Human Rights Watch (HRW) criticised the US over the Abu Ghraib prison abuse scandal in Iraq and the treatment of prisoners at Guantanamo Bay in Cuba.

Shocking pictures last year alerted the world to abuses at Baghdad's Abu Ghraib prison, and there have been numerous allegations of abuse and torture by former Guantanamo Bay inmates.

One FBI agent described in a memo seeing prisoners at Guantanamo shackled, hand and foot, in a foetal position for up to 24 hours at a time, and left to defecate on themselves.

The US defence department has announced a new investigation into the allegations.

It has condemned the abuses in Iraq and says it is prosecuting those responsible.

Mr Ridge told BBC News 24's HARDtalk: "By and large, as a matter of policy we need to state over and over again: we do not condone the use of torture to extract information from terrorists."

But he said it was "human nature" that torture might be employed in certain exceptional cases when time was very limited.

In the event of something like a nuclear bomb threat "you would try to exhaust every means you could to extract the information to save hundreds and thousands of people", he said.

'When not if'

But he admitted there was "a real question" whether using torture on terrorists would actually gain the information required "given the nature of the enemy".

He said the US did not have the luxury of knowing where and when a terrorist attack might happen.

"I don't think it is 'if'. I think it's a matter of 'when'. We operate that way," he said.

"On a day-to-day basis, not just the United States but many allies around the world, do whatever we can to share information about terrorists, share information about the kind of attacks."

Thursday's HRW report called for the Bush administration to set up a fully independent commission to investigate allegations of torture during interrogations at Abu Ghraib.

It said abuses committed by the US had significantly weakened the world's ability to protect human rights because it had undermined international laws.

Mr Ridge argued the HRW report reflected a "foreign perception" that the US was using different methods to those employed before the 11 September 2001 attacks.