Only five – the US, Hungary, Israel, Australia and the Maldives – voted with the UK and 56 abstained.

The UK’s closest European allies, including France, Germany, the Netherlands, Portugal, Poland and Romania, chose to abstain.

Others, among them Austria, Greece, Ireland, Spain, Sweden and Switzerland, voted for the UK to relinquish sovereignty, as did Russia and China.

British control of Chagos Islands is ‘keeping world safe’, claims UK minister

British diplomats said the resolution would have little practical impact.

The UK retained possession of the Chagos Archipelago after Mauritius gained independence in 1968.

The island, known by the Foreign Office as the British Indian Ocean Territory (BIOT), includes the site of a US military base on Diego Garcia, used by bombers on long-range missions and, in the past, for rendition flights carrying terrorism suspects.

Both the UK and US lobbied intensely at the UN to avoid support for Britain dropping to single figures among the UN’s 193 member states.

The Mauritian Prime Minister Pravind Jugnauth, was also present for the debate.

The general assembly vote followed an advisory opinion issued by the International Court of Justice (ICJ) in February declaring the UK should hand over control to Mauritius, which claims sovereignty over the islands.

After the vote, Karen Pierce, the UK’s permanent representative at the UN, said the large number of abstentions reflected many countries’ unease about the precedent set by the motion.

During the debate in New York, Pierce called on other nations to “reflect” on the “unwelcome precedent” of voting for Senegal’s motion, which she said would subject bilateral boundary disputes between countries to enforced resolution at international courts.

“The resolution goes beyond the advisory opinion [at the International Court of Justice in The Hague],” she said.

“It says there will be a six-month deadline for the UK” and could have a wide range of potential implications for the defence of the islands.

Pierce said the US government had made clear that the status of the territory was essential to the value of the joint function of the Diego Garcia base.

During the debate the Maldives representative said her country would not support the motion because of the “serious implications for the security of the Indian Ocean region”.

However, the Cypriot representative said his country supported the motion, pointing out that removal of “parcels of land” in the process of decolonisation usually involved an element of coercion.

The Foreign Office is eager to maintain good relations with Mauritius, a fellow Commonwealth member, despite the dispute.

The UK views BIOT’s defence and security role as vital: the islands are close to some of the busiest shipping lanes in the world.

Diego Garcia is a pivotal location for monitoring and tackling drugs trafficking, piracy and crime in the Indian Ocean and has been used as a base for supporting humanitarian responses, such as after the 2004 tsunami.

The UK government publicly acknowledged in 2008 that Diego Garcia had twice been used, in 2002, for US rendition flights. It has received assurances that the base will not be used for rendition in the future.

Ahead of the result, the UK government was resigned to many countries voting against it on the totemic issue of decolonisation. Diplomats do not believe that Brexit – distancing the UK from its normal European allies – affected the outcome.

In 2017, 15 countries including Britain and the US voted to oppose a request for the ICJ ruling.

Additional reporting by Agence France-Presse