 Britain created the world's biggest marine reserve in its Indian Ocean territory on Thursday, pleasing environmentalists but angering exiled Chagos Islanders who say it creates an obstacle to them returning home. Foreign Secretary David Miliband ordered the creation of a marine reserve, where commercial fishing is banned, in the British Indian Ocean Territory, made up of 55 tiny islands, including Diego Garcia, which houses a U.S. air base. Some 2,000 Chagos Islanders were forcibly removed from the archipelago in the 1960s and '70s to make way for the American base and have waged a long legal battle for the right to return. Representatives of the Chagos Islanders, who have now taken their case to the European Court of Human Rights, argue that the creation of the reserve will stop them returning home because it bars fishing, their main livelihood. The new "marine protected area" will cover a quarter of a million square miles -- an area larger than California -- and doubles the area of the world's oceans under protection. "Its creation is a major step forward for protecting the oceans," Miliband said in a statement. The decision by the British government comes weeks before an election that Conservatives are favourites to win. The U.S.-based Pew Environment Group, one of a number of conservation groups that campaigned for the creation of the marine reserve, called Miliband's decision "a historic victory for global ocean conservation." It said the Chagos Islands rivalled the Galapagos Islands and the Great Barrier Reef in ecological diversity and the area was important for research on climate change, ocean acidification, the resilience of coral reefs and sea level rise. SAFE HAVEN FOR WILDLIFE It said the islands provided a safe haven for dwindling populations of sea turtles and more than 175,000 pairs of breeding sea birds. The sparklingly clean waters around the islands are home to 220 species of corals and more than 1,000 species of reef fish, it said. But islanders and their supporters said the move could be used to prevent them returning home. "They will say that if you go there, you are not allowed to fish. How are you going to feed yourself? How are you going to get your livelihood?," Roch Evenor, an islander who chairs the UK Chagos Support Association, told Channel 4 News. Marcus Booth, vice-chair of the association, which supports islanders' right to return home, accused the government of disregarding the islanders' rights in a rushed move to secure an environmental legacy before the election. Diego Garcia became an important base for the United States during the Iraq and Afghanistan conflicts, acting as a refuelling site for long-range bombers. In 2008, Britain acknowledged that two U.S. planes carrying terrorism suspects had refuelled there six years earlier. Several British courts ruled that evicted islanders and their descendants had a right to return home but Britain's highest court overturned those rulings in 2008. The islanders and their descendants are now believed to number about 5,000. Around a fifth are looking to resettle on the islands, which have belonged to Britain since 1814.