Britain secretly assured the US that establishing a marine park around the Indian Ocean military airbase of Diego Garcia would prevent the return of its original inhabitants, according to leaked diplomatic papers.
The confidential assurance appears to contradict public comments from the Foreign Office that the creation of the environmental haven would have no impact on more than 2,000 Chagos Islanders who wish to return.
The Islanders, described privately by a Foreign Office official as "Man Fridays", were evicted in the 1960s and 1970s to make way for the US airbase, and are currently fighting a legal battle in the European Court of Human Rights (ECHR) to be allowed to return.
Announcing the creation of the world's largest marine park, covering a quarter of a million square miles and containing 55 tiny uninhabited islands in the British Indian Ocean Territory (BIOT), former foreign secretary David Miliband said in April that it would not prejudice the outcome of the ECHR case, expected next year.
And a Foreign Office consultation paper on the proposed conservation area said it would have "no direct immediate impact on the Chagossian community", who had expressed fears that a ban on fishing within the park would prevent them ever returning home.
But a 2009 cable from the US embassy, obtained by whistleblowing website WikiLeaks and published by The Guardian, now appears to suggest the Foreign Office saw the marine park as a means of ensuring the Chagos Islanders would never go back to Diego Garcia.
According to a US diplomat, Foreign Office overseas territories director Colin Roberts said in a private meeting that "establishing a marine park would, in effect, put paid to resettlement claims of the archipelago's former residents". The cable said: "Roberts stated that, according to the HMG's current thinking on a reserve, there would be 'no human footprints' or 'Man Fridays' on the BIOT's uninhabited islands."
Asked about public support for the islanders' continuing campaign for repatriation, Mr Roberts reportedly "opined that the UK's 'environmental lobby is far more powerful than the Chagossians' advocates'."
According to the cable: "He agreed that the UK and US should carefully negotiate the details of the marine reserve to assure that US interests were safeguarded and the strategic value of BIOT was upheld. He said that the BIOT's former inhabitants would find it difficult, if not impossible, to pursue their claim for resettlement on the islands if the entire Chagos Archipelago were a marine reserve."
A Foreign Office spokesman said: "We reject any allegation that the FCO deliberately misled or failed in our obligation to inform Parliament. As we have made clear to Parliament and the public on many occasions, the decision to establish a Marine Protected Area is without prejudice to the current proceedings at the European Court of Human Rights."