Obsolete

The appeal court voted last year that if evidence was obtained under torture by agents of another country with no involvement by the UK, it was usable and there was no obligation by the government to inquire about its origins.

t also means the home secretary, Charles Clarke, must re-examine all cases where evidence from abroad has been obtained by torture.

Commenting on the ruling, Mr Clarke said the government did not condone torture in any way, so the Law Lords' decision was "hypothetical".

"We accept this judgment, which will have no bearing on the government's efforts to combat terrorism: we have always made clear that we do not intend to rely on or present evidence ... which we know or believe to have been obtained by torture," he said.

The detainees, most of whom have been in custody since 2001, were held under Anti-Terrorism Crime and Security Act, which was passed soon after the September 11 attacks in the US.

With the backing of a coalition of human rights groups, they challenged a ruling by the special immigration appeals committee (SIAC) that the Home Office had "sound material" to back up the decision that they posed a threat to national security.

The panel said all eight cases should be sent back to SIAC to be reconsidered.

Lord Bingham of Cornhill, the former Lord Chief Justice who headed the panel, said English law had regarded "torture and its fruits" with abhorrence for more than 500 years.

"The principles of the common law, standing alone, in my opinion compel the exclusion of third-party torture evidence as unreliable, unfair, offensive to ordinary standards of humanity and decency and incompatible with the principles which should animate a tribunal seeking to administer justice," he said.

The human rights groups welcomed the announcement. Amnesty International, which led the coalition on the detainees' behalf, said the decision meant the government must reaffirm its ban on torture and evidence obtained by torture.

An Amnesty spokesman said: "This is a momentous decision. The Law Lords' ruling has overturned the tacit belief that torture can be condoned under certain circumstances.

"This ruling shreds any vestige of legality with which the UK government had attempted to defend a completely unlawful and reprehensible policy introduced as part of its counter-terrorism measures."

Shami Chakrabarti, the director of civil rights group Liberty, said: "This is an incredibly important day, with the Law Lords sending a signal across the democratic world that there is to be no compromise on torture.

"This is also an important message about what distinguishes us from dictators and terrorists. We will not legitimise evidence obtained by torture by using it in our justice system."

Amnesty International is now calling for an end to the deportation of alleged terror suspects to countries where they are at risk of torture.