The UN General Assembly has overwhelmingly voted for a resolution demanding Britain withdraw its administration of the Chagos Islands.

The 193-member world body approved a resolution supporting an advisory opinion made by the International Court of Justice in February that ruled the UK’s decolonisation of the Indian Ocean islands was unlawful.

The vote was 116-6 in favour, with 56 abstentions.

While the resolution is not legally-binding, it carries significant political weight since the ruling came from the UN’s highest court and the assembly vote reflects world opinion.

The court said in its opinion that Britain had unlawfully carved up Mauritius, which the Chagos Archipelago was a part of, in 1965 when Mauritius was a British colony. It said that “the United Kingdom is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible.” The Indian Ocean archipelago is home to the Diego Garcia US military base.

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

Britain disputes that the islands, which it calls the British Indian Ocean Territory, were ever a colony.

Britain’s UN ambassador, Karen Pierce, told the assembly: “British Indian Ocean Territory has been under continuous British sovereignty since 1814. Mauritius has never held sovereignty over it and we do not recognise their claim.”

Ms Pierce expressed disappointment at the General Assembly vote, which saw only the US, Australia, Hungary, Israel and the Maldives support Britain.

But she said the islands remain under British sovereignty, “and it is not in our plan to give the islands to Mauritius”.

Ms Pierce said the UK stands by the 1965 agreement with the Mauritian Council of Ministers to detach the British Indian Ocean Territory in exchange for fishing rights and other benefits and a commitment “to cede the territory when it is no longer needed for defence purposes”.

She stressed the importance of the US and UK defence facility on Diego Garcia to the safety and security of allies and friends, including Mauritius, in the region and beyond in the current “dangerous and uncertain” world.

“It is vital to efforts to combat conflict, terrorism, drugs, crime and piracy,” Ms Pierce said.

Mauritius prime minister Pravind Kumar Juqnauth told the assembly the court’s landmark opinion “confirms the longstanding position of Mauritius and Africa that the decolonization of Mauritius ... will not be completed until Mauritius is able to exercise sovereignty over the Chagos Archipelago”.

He said Mauritius “is extremely disappointed” in the position of the British government, noting Labour Party leader Jeremy Corbyn “has made clear his respect and support for the court’s conclusions”.

Mr Jugnauth said the 1965 agreement on the Chagos Archipelago “was carried out under duress.”

The prime minister said Mauritius has made public commitments at the General Assembly and at the International Court of Justice “that it is prepared to enter into a long-term arrangement with the US, or with the UK and the US, which would permit the unhindered operation of the defence facility in accordance with international law.”

Mr Jugnauth said the court established the right of the people of Mauritius to self-determination which the UK violated “by excising the Chagos Archipelago” without their consent. He said all nations, including the UK, are obligated to comply with international law.

Britain evicted about 2,000 people from the Chagos Archipelago in the 1960s and 1970s so the US military could build the air base on Diego Garcia. Many resettled in the UK and have fought in British courts to return to the islands.

Mr Jugnauth said their forcible eviction “remains a very dark episode of human history akin to a crime against humanity.” But he said the court’s advisory opinion gave “these Mauritian nationals who are now mostly in their 70s and 80s “a glimmer of hope”.

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Mr Jugnauth said the court left it to the General Assembly to decide how rapidly Britain should hand over the islands and the African group, which drafted the resolution, decided on six months.