The United States must provide binding commitments over its future use of the British territory of Diego Garcia in the Indian Ocean if it is to be allowed to carry on using its vast military base on the island, MPs have said.
The Commons Foreign Affairs Committee said public confidence had been "dented" by the disclosure in 2008 that the US had secretly used the island as part of its "extraordinary rendition" programme without informing British ministers - in contravention of previous assurances.
The committee said the Government should use the forthcoming negotiations on the renewal of the 50-year agreement allowing the US to use the island - which runs to 2016 - to tighten up the previous informal arrangements.
It said that a requirement to obtain the prior approval of the UK Government for the use of island in combat operations or other "politically sensitive activity" should be written into the new agreement - with an explicit condition that it must not be used for rendition without authorisation from UK ministers.
The committee chairman, Sir Richard Ottaway, said: "We believe that would concentrate minds and prevent a recurrence of the unhappy events of 2008."
He added: "This is about building confidence. The Government relied on US assurances on its use of Diego Garcia, and in 2008 these proved to be inaccurate. That severely damaged credibility. The British public is entitled to know that the UK is able to exercise control over its sovereign territory and what happens there."
In 2006, the then foreign secretary Jack Straw told MPs that there was no evidence that the US had used any British overseas territory in the rendition of terrorist suspects following the 9/11 attacks in 2001.
Two years later, however, the then incumbent David Miliband disclosed that the US had since admitted it had used Diego Garcia for the re-fuelling of rendition flights on two occasions in 2002 without informing the UK.
Earlier this year, it was reported that an as yet unpublished US Senate committee inquiry had found that the CIA had a so-called "black site" on the island which it used for the detention of "high value suspects" with the "full co-operation" of the UK government.
"If these reports are substantiated, we would expect to revisit this issue, to assess the implications for the UK and for public confidence in its statements on US use of Diego Garcia," the committee said.