Britain has said it won't implement the Chagos deal without US support 

The United Kingdom has halted a plan to hand over the Chagos Islands, an Indian Ocean archipelago, to Mauritius.

British Prime Minister Keir Starmer signed an agreement last year transferring sovereignty of the islands to Mauritius. However, the deal allowed Washington and London to retain control of the joint military base on Diego Garcia Island for an initial period of 99 years.

US President Donald Trump said in February that the plan to hand over the archipelago to Mauritius, while retaining control of the joint US-UK military base of Diego Garcia through a lease, was a "big mistake." 

On Sunday, the UK said it continued to believe the agreement is the best way to protect the long-term future of the base, but added the condition of US support.

"Diego Garcia is a key strategic military asset for both the UK and the US," a UK government spokesperson said. 

"We have always said we would only proceed with the deal if it has US support. We are continuing to engage with the US and Mauritius," the spokesperson added.

The development also comes amid opposition to the planned move in the UK from the Conservatives and Reform Party.

Mauritius has said it will hold talks with UK officials on April 22 to discuss the issue, Bloomberg reported.

In 1965, the UK promised to withdraw from Mauritius, but it removed the Chagos Archipelago from the jurisdiction of Mauritius, paying the latter Pound 3 million in compensation.

In 1966, despite the UN's objections to British control over the archipelago, the UK leased Diego Garcia to the US for 50 years in exchange for a $14 million discount on the purchase of Polaris ballistic missile submarines. 

The joint US-UK military base, equipped with a runway, is used for positioning navy ships and long-range bombers. 

In March, the Maldives told the UK that it does not recognize the deal to hand over the Chagos Islands to Mauritius. It has now welcomed the decision to pause the handover of the Chagos Archipelago.

The Maldives says it has historical claims to the archipelago.