The British government's problems with missing files have deepened dramatically after the Foreign Office claimed documents on the country's role in the CIA's global abduction operation were destroyed accidentally when they became soaked with water.
In a statement human rights groups said "smacked of a cover-up", the department maintained that records of flights after September 11, 2001 in and out of Diego Garcia, the British territory in the Indian Ocean, were "incomplete due to water damage".
The claim comes amid media reports in the United States that a Senate report due to be published later this year identifies Diego Garcia as where the CIA established a secret prison as part of its extraordinary rendition programme. According to one report, classified CIA documents state that the prison was established with the "full co-operation" of the British government.
It also comes at a time when members of Parliament are demanding the Home Office, Britain's interior ministry, urgently provide more information about 114 "missing" files that could have contained information about an alleged child abuse network in the 1980s.
Ministers of successive governments have repeatedly given misleading or incomplete information about the CIA's use of Diego Garcia. In February 2008, the then foreign secretary, David Miliband, was forced to apologise to MPs and explain that Tony Blair's "earlier explicit assurances that Diego Garcia had not been used for rendition flights" had not been correct.
The "water damage" claim was given in response to a parliamentary question by the Conservative MP and chair of the Treasury select committee Andrew Tyrie, who has been investigating the country's involvement in the rendition programme for years.
When Tyrie asked the Foreign Office to explain which government department keeps a list of flights which passed through Diego Garcia from January 2002 to January 2009, Foreign Office minister Mark Simmonds replied: "Records on flight departures and arrivals on Diego Garcia are held by the British Indian Ocean Territory immigration authorities. Daily occurrence logs, which record the flights landing and taking off, cover the period since 2003. Though there are some limited records from 2002, I understand they are incomplete due to water damage."
Cori Crider of the legal charity Reprieve said the claim that documents had been destroyed accidentally was "especially disturbing" given that Scotland Yard is investigating the role played by British foreign intelligence in the abduction of a Libyan dissident, Abdel Hakim Belhaj, who was flown to one of Muammar Gaddafi's prisons along with his pregnant wife in 2004.
The police investigation, Operation Lydd, is thought to have examined whether the couple were flown via Diego Garcia. A report is due to be handed to the director of public prosecutions.
The White House and the CIA are working on final redactions to a 481-page executive summary of a classified report by the US Senate committee on intelligence on the rendition programme prior to its publication, possibly in September. The full 6,300-page report is said to be scathing of the way in which the CIA resorted rapidly to the abduction and torture of al-Qaeda suspects after the attacks of 2001.
There have been a number of reports suggesting that allies of the US, including Britain and Poland, have been lobbying to ensure all reference to their own involvement is removed from the summary before it is published.