Foreign Secretary David Miliband said that both cases involved refueling on Diego Garcia, which is home to a U.S. base, the BBC reported. The planes were carrying prisoners subject to "extraordinary rendition" -- the practice of turning over a suspect for questioning by another country.

U.S. officials said that neither prisoner was British, both remained on board while the planes were refueled and neither was subjected to torture or waterboarding, Miliband said.

The British government position is that the United States cannot use British airspace for rendition flights without permission. Both former British Prime Minister Tony Blair and former Foreign Secretary Jack Straw made statements that Miliband said were in "good faith" that no rendition flights were using British airspace or territory.

William Hague, the shadow foreign secretary for the Conservatives, told the BBC he accepts that Straw and Blair believed what they were told but finds their statements a concern.

"More worrying still, it means that very specific assurances about the use of the facilities at Diego Garcia have also turned out, although given in good faith, to have been false," he said.