The UK Foreign Office (FCO) has further delayed publication of flight records for Diego Garcia, following disclosures by a senior Bush administration official that interrogations took place at a CIA black site on the British island.

FCO officials are "still assessing the suitability of the full flight records for publication", nine months after they were first requested from the government by human rights NGO Reprieve.

Campaigners believe that the logs — written records of all flights landing on and leaving the atoll — could provide crucial, previously undisclosed details of flights involved in the intelligence agency's post-9/11 rendition and torture program.

'It is now over seven years since the UK government was forced to admit that CIA torture flights were allowed to use the British territory of Diego Garcia, yet we still seem no closer to the publication of flight records which could provide crucial evidence of what went on.'

However, the UK government has so far declined to publish the logs, and has dismissed the new claims made by a former senior Bush administration official — published by VICE News — that the CIA did in fact detain prisoners on Diego Garcia, despite years of assurances from British ministers to the contrary.

"We have responded publicly in recent years to previous claims," wrote Hugo Swire, the FCO minister of state, in a letter to Reprieve. "However, Colonel Wilkerson has not presented any new evidence to support his allegation that detainees were held on Diego Garcia."

Lawrence Wilkerson, former chief of staff to Secretary of State Colin Powell, told VICE News in January that the island was home to "a transit site where people were temporarily housed, let us say, and interrogated from time to time." His information came from four well-placed CIA and intelligence sources, he said.

Swire said that the British government "seeks regular reassurance from the US government" on renditions, in the letter dated March 3.

"All previous assurances on transfer of detainees provided by the US government since 2008 remain valid and correct," Swire wrote.

"Whilst I am not able to make public the details of diplomatic correspondence, I can confirm that the most recent assurances were received this month."

Swire did not explain whether the FCO contacted the US in direct response to Wilkerson's disclosures, but did say that the most recent assurances were made "after Colonel Wilkerson's claims were made."

Donald Campbell of Reprieve said the publication of the flight logs was necessary to reassure the public that Britain is not involved in a cover-up of torture evidence.

"It is now over seven years since the UK government was forced to admit that CIA torture flights were allowed to use the British territory of Diego Garcia," he said, "yet we still seem no closer to the publication of flight records which could provide crucial evidence of what went on.

"Last summer, after the records reportedly suffered 'accidental' water damage, ministers promised that they were 'assessing their suitability for publication.' Eight months later, they say they are still 'assessing.' It is hard to see how such a long delay could be justified."

It is far from the first time that Diego Garcia's role in the CIA's post-9/11 rendition and torture program has been disputed.

The tiny atoll in the Indian Ocean, which has been leased to the US for use as a military base since 1966, has been the subject of CIA torture program claims and counter-claims stretching back more than a decade. The release of the Senate Intelligence Committee torture report in December confirmed that the CIA did operate a post-9/11 global rendition and torture program, with secret prisons all over the world — but the heavily redacted document did not reveal whether Diego Garcia was a part of the CIA's international network of black sites.

The UK's changing position on Diego Garcia's unpublished flight records

The British government says it has received repeated assurances from the US that no CIA rendition flights landed on Diego Garcia — bar two rendition planes which stopped briefly to refuel in 2002.

The government has been slow to release flight logs for the atoll, however, and the position of the Foreign Office in relation to the records has shifted as pressure for them to be released has grown.

February 21 2008: The UK admits that two rendition flights stopped over on Diego Garcia to refuel.

David Miliband, then the foreign secretary, tells parliament he is "very sorry indeed" to report that contrary to earlier assurances, two rendition flights carrying a single detainee each did, in fact, land on Diego Garcia.

July 2008: ... but the UK claims that records on these two flights — and for the whole of 2002 — are no longer held.

Miliband tells the Intelligence and Security Committee (ISC) that records "are unfortunately no longer held for the period when the two cases of rendition occurred [2002]," because they are generally only held for up to five years.

June 26 2014: NGO Reprieve asks the foreign secretary whether flight records from 2002 onwards are held...

Reprieve writes to William Hague, who has by then taken over as foreign secretary, asking: "Can you confirm whether the government holds monthly statistics of flights through D[iego] G[arcia] from January 2002 onwards; daily logs from October 2002 onwards; and general aviation reports from January 2004 onwards? And can you confirm that all planes and flights recorded in all these logs and statistics have been investigated, and discounted as being possible rendition flights?"

July 8 2014: ...and the Foreign Office says they are held, but 2002 flight records are incomplete due to 'water damage.'

Mark Simmonds, a Foreign Office minister, tells members of parliament (MPs) that "though there are some limited records from 2002, I understand they are incomplete due to water damage."

July 14 2014: ... but then the foreign secretary says he believes that there's actually a complete set of flight logs for 2002.

Hague replies to Reprieve's letter saying that actually only a small number of flight records have been irretrievably damaged: "I am satisfied that for the period you are asking about, we have a complete set of information about types of aircraft, passenger and crew numbers landing and departing Diego Garcia."

July 15 2014: The Foreign Office confirms that the water damaged 2002 flight records have not been lost after all — because they've "dried out."

Foreign Office Minister Mark Simmonds tells MPs that water-damaged records have "dried out": "Since my answer of 8 July, BIOT [British Indian Ocean Territory] immigration officials have conducted a fuller inspection, and previously wet paper records have been dried out. They report that no flight records have been lost as a result of the water damage."

He says that "a small number of immigration arrival cards from 2004" have been damaged, however.

August 19 2014: The Foreign Office says that not all flight records from 2002 onwards are complete, but they should be able to get a full set anyway.

Responding to a letter from Reprieve asking for clarification on which flight records are damaged, Philip Hammond, now foreign secretary, writes: "The Administration of the British Indian Ocean Territory holds several different types of record about flights entering the territory, though not all of these are complete for the period you are referring to. By combining different types of records, we are confident we can establish what types of aircraft landed on a particular day, and passenger and crew numbers on these aircraft, for the period since 2002."

September 4 2014: It turns out the heavy weather that damaged the records wasn't so heavy after all...

VICE News obtains the government's own records which show that the so-called "extremely heavy weather" in June 2002 amounted to 3.25 inches of rainfall — considerably less than the average for that month.

"I don't think it's very helpful for us to have a discussion about how much rain is a lot of rain," a FCO spokesperson told VICE.