The Argentinian government has begun legal action seeking to stop the exploration of oil and gas fields north of the Falkland Islands in an escalating row with the UK.
Buenos Aires said in a statement the request lodged with the International Tribunal for the Law of the Sea aimed to block activity authorised "illegally" by the UK.
The claim comes a fortnight after Argentinian President Javier Milei demanded the scrapping of the Sea Lion oilfield project, a joint venture between Israeli and British companies.
UK Foreign Office minister Uma Kumaran criticised the "escalating campaign" from Argentina against companies operating in the Falklands, while announcing new protections for them.
The developments heighten tensions between the UK and Argentina over the sovereignty of the self-governing British territory, known in Argentina as Las Malvinas, more than 40 years after a British military task force ejected Argentinian forces which had invaded the territory.
Earlier last month Milei also threatened to impose economic sanctions on firms exploiting oil close to the Falkland Islands.
Uma Kumaran accused the Argentinian government of "economic coercion" against the people of the Falkland Islands.
"We will do whatever it takes to support them," she told the House of Commons on Tuesday.
The Sea Lion oilfield, around 130 miles (209 km) from the Falkland Islands, contains an estimated 1.7 billion barrels of oil.
The Falkland Islands government extended exploration licences last month and the field is expected to start pumping in 2028, potentially generating huge revenues for the roughly 3,500 inhabitants of the islands.
Two oil companies – Britain's Rockhopper Exploration and Israel's Navitas Petroleum – have insisted they have valid licences issued by Britain.
The Argentinian government claims the marine environment of disputed maritime areas is protected by international law.
Its application "seeks to preserve Argentina's sovereign rights over its continental shelf and prevent activities authorised unilaterally and illegally by the United Kingdom".
In a post on X, Argentinian Foreign Affairs Minister Pablo Quirno said the government was requesting the tribunal make a number of orders against the UK, including halting new exploration permits.
But the UK government insists Sea Lion is lawful, located on the Falkland Islands shelf and regulated by the islands' government.
While the Falkland Islands government grants exploration licences, they must be signed off by the UK Foreign Secretary.
Kumaran said the tribunal application "does not invalidate licenses issued by the Falkland Islands government, alter the islands' regulatory authority, or require lawful hydrocarbon development activities to cease".
The tribunal that will consider the dispute is an independent judicial body based in Hamburg which is responsible for the fair application of the United Nations' Convention on the Law of the Sea.
FCDO officials have made clear the UK will engage with the tribunal but resist Argentina's claim firmly.
They said the aim was not to escalate the dispute but respond firmly to Argentina's latest move, and defend what the UK sees as legitimate economic activity.
They also hope to provide reassurance to businesses fearful of Argentine retribution. That is why they are introducing measures under the Protection of Trading Interests Act that would protect firms from any extra-territorial impact of Argentine laws following Milei's sanctions threats.
Foreign Secretary Ed Miliband said: "Argentina's attempts to intimidate businesses and individuals engaged in legitimate commercial activity are unacceptable. Companies should be free to make lawful commercial decisions without the threat of political coercion."
The latest move comes after Milei roundly criticised the UN in his speech at the General Assembly late last month for failing to act over the sovereignty of the Falkland Islands.
He said the UN had become "a useless organisation" which only serves "arrogant parasites dressed up as well-intentioned bureaucrats".
On Tuesday Kumaran described Milei's remarks at New York as "inflammatory".
Despite its defeat in 1982, Argentina has always maintained its right to the Falkland Islands. But over the years successive governments have pressed their claim with varying degrees of aggression and diplomacy.
UK officials believes the current Argentine leadership is deliberately picking a fight ahead of elections next year.
