Indian Ocean islanders who were forced into exile to make way for a huge U.S. military base have lost a legal ruling in their long-running campaign to return home.

The High Court in London ruled Tuesday that the British government can establish a marine reserve around the Chagos Islands.

Britain forced thousands of people to leave the islands, a British colony, in the 1960s and 1970s so the U.S. military could build an air base on Diego Garcia, the largest of the islands.

The former residents have fought a long and unsuccessful legal battle to return.

The islanders argued that the marine reserve was being created to block them. But two High Court judges accepted the government's claim that the reserve was being created for environmental and conservation purposes.