Britain has said the sovereignty of the Falkland Islands is not up for negotiation, after Argentina’s newly-elected president promised to “get them back”.

Javier Milei, who won a resounding victory in Argentina’s presidential election on Sunday, said Buenos Aires had “non-negotiable” sovereignty over the Falklands, the archipelago in the South Atlantic Ocean which is known as Islas Malvinas in Argentina.

Mr Milei said during a TV debate in the run-up to the election that “we have to make every effort to recover the islands through diplomatic channels”.

On Tuesday a spokesperson for prime minister Rishi Sunak said: “The UK has no doubt about the sovereignty of the Falkland Islands, and indeed South Georgia and the South Sandwich Islands.

“The UK government will continue to proactively defend the Falkland islanders’ right to self determination.”