The Prime Minister of Mauritius has branded the United Kingdom an 'illegal colonial occupier' after the British government ignored a United Nations deadline to return the Chagos Islands.

The British government does not recognise Mauritius' sovereignty over the archipelago in the Indian Ocean, however Mauritius claims it was forced to trade sovereignty over the islands for independence in 1965.

The United Nations demanded the UK hand over administration of the Chagos Islands to Mauritius in May, and gave the British government a six-month deadline to comply with the resolution, which lapsed on Friday.

The UN General Assembly had adopted the resolution based on findings by the UN's International Court of Justice (ICJ) that Britain must surrender control of the archipelago.

Prime Minister Boris Johnson said the UK disputes Mauritius's claim of sovereignty. He told reporters: 'We obviously dispute the claims that are made and we will continue to make those to vindicate our position in international law.'

Labour leader Jeremy Corbyn vowed to 'end colonial rule' and return the islands if he wins the December 12 election, and accused the Conservatives of 'shamefully' considering themselves above international law.

The UN Assembly backed by 116 votes to six a verdict by the ICJ that the UK's detachment of the islands and their incorporation into the British Indian Ocean Territory was 'unlawful' (pictured: Diego Garcia, a British Indian Ocean Territory and the largest of the islands in the Chagos Archipelago)

Chagos islanders outside the High Court in London in 2007, where they were fighting the UK government for the reinstatement of their homeland

The Foreign Office said the joint UK-US defence facility on the British Indian Ocean Territory 'helps to keep people in Britain and around the world safe from terrorism, organised crime and piracy'

At the UN in May 116 countries voted in support of an African resolution urging Britain to 'withdraw its colonial administration' from the Chagos Islands within six months, and hand them to Mauritius.

Only six countries, including Britain and the US, opposed the motion. The non-binding vote came after the International Court of Justice in the Hague ruled Britain's control of the islands was unlawful.

The Chagos Refugee Group staged a demonstration outside the British High Commission in Mauritius yesterday.

Spokesman Olivier Bancoult said: 'This peaceful demonstration is intended to show the discontent of the Chagossians and Mauritians at Britain's refusal to respect the United Nations resolution, adopted on May 22, and giving her six months to end the illegal occupation.

'Until now, Britain has shown no interest at the request of the UN and has made it clear that it does not intend to go.'

The Foreign Office said: 'The UK has no doubt as to our sovereignty over the British Indian Ocean Territory, which has been under continuous British sovereignty since 1814.

'Mauritius has never held sovereignty over the territory and the UK does not recognise its claim.'

Britain forcibly evicted people from the islands, a sovereignty in the Indian Ocean disputed by the UK and Mauritius, in the 1960s and 1970s so the United States could build a military base.

Mr Corbyn, speaking to reporters on the campaign trail in Stoke-on-Trent on Friday, said he would 'absolutely' return the islands to Mauritius.

'It's clear that in refusing to return the Chagos Islands to Mauritius and defying the UN General Assembly and International Court of Justice, this Conservative Government shamefully considers itself to be above international law,' he added in a statement.

'We immediately will enact our manifesto promise to allow the people of the Chagos Islands and their descendants the right to return to the lands from which they should never have been removed.'

A UN communique said: 'Since the decolonisation of Mauritius was not conducted in a manner consistent with the right to self-determination, the Assembly affirmed, the continued administration of the Archipelago constitutes a wrongful act.

'It urged the United Kingdom to co-operate with Mauritius to facilitate the resettlement of Mauritian nationals, including those of Chagossian origin, in the Chagos Archipelago and to pose no impediment to such efforts.'

The Foreign Office had previously said the joint UK-US defence facility on the British Indian Ocean Territory 'helps to keep people in Britain and around the world safe from terrorism, organised crime and piracy'.

Speaking in May, Dame Karen Pierce, the UK's ambassador to the UN said: 'The United Kingdom regrets that the General Assembly has today voted to adopt this resolution.

'The United Kingdom fully recognises the importance of the issue of decolonisation and the UN's role in that. The United Kingdom … sincerely regrets the manner in which Chagossians were removed from British Indian Ocean territory in the 1960s and the 1970s and we are determined to improve their lives where they have resettled.'

The UK agreed a package including £3 million with Mauritius for the detachment of the archipelago in 1965.

Chagossians were forcibly removed between 1967 and 1973 to make way for a US military facility on Diego Garcia, the largest island in the group.

Mauritius, which gained independence in 1968, maintains that the islands are its own and Chagossians have also brought cases in British courts for the right to return.

Britain must hand back control of the archipelago to Mauritius within six months, the UN says