LONDON (Reuters) - Britain said for the first time on Thursday the United States had used British territory to transfer terrorism suspects, in an embarrassing apology that corrected previous denials.

Britain, after maintaining for years it was unaware of a British link to such “rendition” flights, said Washington had now told it two planes with detainees refueled at a U.S. base on the British Indian Ocean island of Diego Garcia in 2002.

Allegations of covert U.S. activities as part of the “war on terror” have circulated for years. A European investigator said last year he had proof Poland and Romania hosted secret prisons for the U.S. Central Intelligence Agency.

“Contrary to earlier explicit assurances that Diego Garcia had not been used for rendition flights, recent U.S. investigations have now revealed two occasions, both in 2002, when this had in fact occurred,” British Foreign Secretary David Miliband told parliament.

“In both cases a U.S. plane with a single detainee on board refueled at the U.S. facility in Diego Garcia,” he said.

It is embarrassing for the government, already sensitive to criticism that it is too ready to follow Washington’s line, with Tony Blair, who was prime minister at the time, dubbed in the press as President George W. Bush’s “poodle”.

“It’s unfortunate mistakes were made in the reporting of the information, but we will continue to have good counter-terrorism cooperation between the United States and the United Kingdom,” Gordon Johndroe, spokesman for the White House National Security Council, told reporters traveling with Bush in Liberia.

STAUNCH ALLY

Britain, Washington’s leading ally in the wars in Iraq and Afghanistan, has previously said it was not aware of its territory being used to transfer terrorism suspects outside normal extradition procedures since Bush took office in 2001. Washington has admitted to the practice, known as “rendition”.

Miliband said he was “very sorry indeed” to have to correct earlier government denials, based on new information from the U.S. government.

Washington had told Britain that neither of the detainees was British, Miliband said, without revealing their identity. One was being held at the U.S. prison camp at Guantanamo Bay, Cuba, and the other had been released.

He said the two detainees had not been taken to a secret detention facility and had not undergone water boarding or other similar forms of interrogation.

The U.S. Congress last week voted to ban the CIA from using water boarding, a simulated drowning technique widely condemned by human rights groups as a form of torture.

Miliband said he had discussed the issue on Wednesday with U.S. Secretary of State Condoleezza Rice, who had pledged there would be no renditions through Britain, its air space or territories without express British permission.

Britain would draw up a list of all suspicious flights through Britain or its overseas territories and ask for U.S. assurance that they were not used for rendition, he said.

Miliband agreed the matter was serious but said Britain would continue to have “the strongest possible intelligence and counter-terrorism relationship with the U.S.”