The UK has been called an illegal colonial occupier by Mauritius after failing to meet the UN deadline to return control of an overseas territory to the island nation.

Britain was given six months to return the Chagos Islands after the UN general assembly voted overwhelmingly to condemn its continued occupation of the Indian Ocean territory, but the deadline passed Friday.

Mauritian prime minister Pravind Jugnauth said the UK was now an illegal colonial occupier, according to the BBC.

Mauritius, a former British colony, claims it was forced to trade the Chagos Islands in exchange for independence.

Britain purchased the islands for £3m in 1965, when Mauritius was still a colony. The archipelago is known to the UK government as the British Indian Ocean Territory.

Chagos islanders demand to return home: in pictures Show all 10 1 /10 Chagos islanders demand to return home: in pictures Chagos islanders demand to return home: in pictures Chairman of the Chagos Refugees Group, holds his grandson Julien aloft outside The High Court in central London alongside then backbench Labour MP for Islington North Jeremy Corbyn on May 23 2007. Families expelled from the Chagos Islands by the British Government to make way for the Diego Garcia US airbase won their legal battle to return home Wednesday. The ruling was later overturned after the British government appealed AFP/Getty Chagos islanders demand to return home: in pictures Chagos islanders march by Parliament on October 22 2008. The British government on Wednesday won its appeal to Britain's highest court over previous rulings that allowed displaced islanders to return home AFP/Getty Chagos islanders demand to return home: in pictures Chagos islanders march by Parliament on October 22 2008 AFP/Getty Chagos islanders demand to return home: in pictures Chagos islanders march by Parliament on October 22, 200 AFP/Getty Chagos islanders demand to return home: in pictures A Chagossian man shows his identity card stating his birth place as the Solomon Island, Chagos on January 17 2005 in Port Louis, Mauritius AFP/Getty Chagos islanders demand to return home: in pictures Chagossian Islanders and their supporters arrive at the Court of Appeal in central London on February 5 2007, as they prepare to fight a court ruling which would prevent the islanders from returning to their homes in the remote Chagos archipelago AFP/Getty Chagos islanders demand to return home: in pictures Chagossian islanders outside of the Court of Appeal in London on February 5 2007 protest a court ruling which would prevent them from returning to their home islands AFP/Getty Chagos islanders demand to return home: in pictures Chagossian islanders outside of the Court of Appeal in London on February 5 2007 protest a court ruling which would prevent them from returning to their home islands AFP/Getty Chagos islanders demand to return home: in pictures Chagossian islanders outside of the Court of Appeal in London on February 5 2007 protest a court ruling which would prevent them from returning to their home islands AFP/Getty Chagos islanders demand to return home: in pictures Chairman of the Chagos Refugees Group, holds his grandson Julien aloft outside The High Court in central London alongside then backbench Labour MP for Islington North Jeremy Corbyn on May 23 2007. Families expelled from the Chagos Islands by the British Government to make way for the Diego Garcia US airbase won their legal battle to return home Wednesday. The ruling was later overturned after the British government appealed AFP/Getty

Earlier this year, the UN general assembly voted by an overwhelming majority of 116 to six countries in favour of a motion demanding that the islands, Britain's last remaining African territory, be reunited with Mauritius.

The UN had adopted the motion on the advice of the International Court of Justice (ICJ), which found that the decolonisation of Mauritius was not "lawfully completed" according to international law.

The UK does not regard the judgement of the ICJ nor the UN motion as binding.

A Foreign Office spokesperson said: "We have no doubt about our sovereignty over the British Indian Ocean Territory, which has been under continuous British sovereignty since 1814.

"Mauritius has never held sovereignty over the archipelago and we do not recognise its claim."