The UK government has designated an area around the Chagos Islands as the world's largest marine reserve.The reserve would cover a 544,000 sq km area around the Indian Ocean archipelago, regarded as one of the world's richest marine ecosystems. This will include a "no-take" marine reserve where commercial fishing will be banned. But islanders, who live in exile, have expressed concern that a reserve may in effect ban them from returning. The UK Foreign Secretary David Miliband said establishing the reserve would "double the global coverage of the world's oceans under protection". He commented: "Its creation is a major step forward for protecting the oceans, not just around BIOT [the British Indian Ocean Territory] itself, but also throughout the world. "This measure is a further demonstration of how the UK takes its international environmental responsibilities seriously." Conservationists say the combination of tropical islands, unspoiled coral reefs and adjacent oceanic abyss makes the area a biodiversity hotspot of global importance. The archipelago has been compared to to the Galapagos Islands and is said to possess up to half the healthy reefs in the Indian Ocean. William Marsden, chairman of the Chagos Conservation Trust, commented: "Today's decision by the British government is inspirational. It will protect a treasure trove of tropical, marine wildlife for posterity and create a safe haven for breeding fish stocks for the benefit of people in the region." However, Chagossians have previously said the protected zone could prevent them from fishing - their main livelihood. The former residents, who were evicted from the British overseas territory between 1967 and 1971 to make way for a US Air Force base on the largest island, Diego Garcia, have fought a long-running battle in the UK courts for the right to return. Alistair Gammell, from the Pew Environment Group, said he was "thrilled" with the decision, adding that the oceans "desperately need better protection". He commented: "In 2010, the International Year of Biodiversity, the UK has secured a conservation legacy which is unrivalled in scale and significance, demonstrating to the world that it is a leader in conserving the world's marine resources for the benefit of future generations." The Foreign Office said it had been advised that the BIOT was crucial for repopulating coral systems along the East Coast of Africa and hence to the recovery in the marine food supply in sub-Saharan Africa. The conditions of the marine protected area are expected to be enforced by the territory's patrol vessel.