Argentine President Javier Milei says his government will seek international arbitration against Britain over an oil project off the disputed, UK-controlled Falkland Islands.

Milei’s office said it had given Britain two weeks to halt work on Sea Lion, an offshore oilfield being developed by Israel’s Navitas Petroleum and Britain’s Rockhopper Exploration.

Otherwise, Argentina would ask the International Tribunal for the Law of the Sea to order a temporary halt to the project.

“Argentina will not stand idly by,” the presidential statement said, accusing Britain of causing “irreversible and irreparable” harm to Argentina’s sovereign rights.

The tribunal, an independent maritime court in Hamburg, established under the 1982 UN Convention on the Law of the Sea, can issue legally binding emergency orders. But even if it ordered Britain to halt the project, it has no way to force the government to comply.

Britain rejects Argentina’s sovereignty claim, arguing the islanders have the right to determine their own future and develop their natural resources. In a 2013 referendum, residents of the Falklands voted overwhelmingly to remain a British overseas territory.

Argentina contends the islands were populated illegally.

Foreign Minister Pablo Quirno hailed Milei’s move as “a historic and unprecedented step” in Argentina’s nearly two-century campaign to secure sovereignty over the archipelago.

“Whoever explores or exploits our natural resources in the Malvinas without Argentine authorisation must face the consequences,” he wrote on X, using Argentina’s name for the islands.

Milei, a self-described “anarcho-capitalist”, initially sought warmer ties with Britain and professed admiration for Margaret Thatcher, the wartime British prime minister loathed in Argentina for ordering the islands’ recapture.

The brief but bloody war, which erupted when the Argentine military dictatorship invaded the archipelago in 1982, killed 649 Argentine troops, 255 British service members and three islanders.

Milei has taken an increasingly confrontational stance as oil production near the islands approaches its anticipated start in 2028. US President Donald Trump, a close ally of the Argentine leader, has also suggested he could reconsider Washington’s longstanding neutrality in the dispute.

-AAP