The talks, held on Friday afternoon, marked the first time both Sir Keir Starmer and Navin Ramgoolam had spoken to each other directly.
The prime minister has pressed Mauritius on the need for the Chagos Islands deal to allow “strong protections” for the UK-US military base there.
Sir Keir Starmer spoke to his Mauritian counterpart on Friday afternoon, Downing Street said.
During their conversation, the Labour leader told Navin Ramgoolam he wanted “strong protections” for the UK-US military base on Diego Garcia as talks to hand them over to Mauritius continue.
This marked the first time the two leaders have spoken directly since they both came to power.
It came after Mr Ramgoolam previously ordered an independent review of his predecessor’s provisional deal with the UK, soon after coming to power.
Giving a readout of the call, a Downing Street spokesperson said: “The prime minister spoke to the prime minister of Mauritius Navin Ramgoolam this afternoon.
“The leaders began by reflecting on their first months in office and discussed the strong relationship between the UK and Mauritius, which they looked forward to expanding.
“The prime minister underlined the need for a deal to secure the military base on Diego Garcia that ensures strong protections, including from malign influence, and that will allow the base to continue to operate.
“Both leaders reiterated their commitment to a deal, and they looked forward to speaking again soon.”
Since 2022, when the Conservatives were in power, the UK has been negotiating a deal with Mauritius to hand over control of the Chagos archipelago.