Foreign Secretary Ed Miliband has said the UK will “resolutely uphold” the self-determination of the Falkland Islands after Argentinian president Javier Milei said his country needed to take them back.

In a national address, Mr Milei reiterated the country’s claim on the islands and said he would introduce sanctions on any oil companies working in the area.

The renewed tensions over the British overseas territory came after US president Donald Trump hinted the US would not help the UK in a future Falklands conflict.

Mr Miliband said in a post on X: “The UK’s position on the Falkland Islands is unwavering.

“The Islands are British and will remain so because that is the overwhelming position of the Islanders.

“Their right of self-determination is paramount, grounded in international law and we will resolutely uphold it.”

Defence Secretary Wes Streeting earlier said the UK’s commitment to the Falklands was “absolute and unshakeable.”

Downing Street suggested there would be no UK diplomatic response to Mr Milei’s threats, with the UK seeking to bolster ties with the country.

In a 2013 referendum, the Falkland Islanders voted overwhelmingly to remain a British overseas territory, with 99.8% voting in favour and just three votes against.

Although the US is formally neutral, Washington provided support for Britain’s campaign to retake the islands after the Argentinian invasion in 1982.

It sparked the Falklands War which saw 255 British service deaths in just over 70 bloody days. It also led to the deaths of 655 Argentinians and three Falkland Islanders.

In his speech, Mr Milei said: “Our role and relevance as a country in the world has changed dramatically.

“The Falklands are our future – we need to recover these islands which are nationally relevant. There is no other path forward.”

He said he would sign decrees to introduce sanctions against any companies working on oil production in the area.

And he declared the Sea Lion oilfield, owned by an Israeli and a British firm where production is expected to begin in 2028, a “clear and present danger” to the country’s claims.

“If we do not act swiftly in a few months, they will have the material capacity to access the oil that lies underneath our sea. Something that has never happened before,” he said.

British-based oil exploration company Rockhopper, which is working with Navitas on the oilfield near the islands, said it did not expect developments by the Argentinian government to have a “material effect” on the project.

A No 10 spokeswoman said the UK supports the right of the Falkland Islanders to develop their natural resources for their own economic benefit, and “this is an integral part of their right to self-determination”.

“Their decision to pursue hydrocarbon production is a commercial decision for them to take alongside the companies involved.”

The Argentinian leader announced plans to boost its defence resources with a new naval base in Tierre del Fuego in the south of the country.

Mr Milei said the US was “assessing their historical position in regard to the Falklands”.

Asked whether there would be a diplomatic response to his threats, the Downing Street spokeswoman said the UK continues “to have a diplomatic relationship with Argentina, and from our perspective we want to continue to strengthen that”.

The US president on Thursday suggested he would not back the UK in a fight over the territory, pointing to the lack of support for his war in Iran.

Asked in an interview if he would “come to the aid” of the UK, the US president told GB News: “Well look, I was there when they had the first war.

“That was a long time ago and I watched it so carefully, and you comported yourselves very well.

“You took it back pretty strongly, but it’s a long way away. That’s a big trip, it’s a long way.

“So, your country’s not doing well. Don’t forget, you get a big percentage of your oil from the Strait of Hormuz, and you weren’t there to help me.

“Your country was not there to help me. We didn’t need help, but I did ask Nato, and I asked your former leader: ‘Why didn’t you send a couple of ships?’

“He said: ‘We don’t have any,’ and it was pretty sad, the whole thing. So Nato was not there, even though they get – most of those countries get – a big portion of their oil from there. So we’re doing that by ourselves.”

No 10 declined to comment on Mr Trump’s remarks, saying they were “a matter for the US president”.

There has been speculation that Washington could be seeking access to the oil produced off the Falkland Islands’ coast.

Sarah Rogers, a senior official in the US state department, wrote on X that “exciting things are happening in the Western Hemisphere” alongside a photo of her and Mr Milei ahead of his speech.

Tory leader Kemi Badenoch said in response to Mr Milei that “Britain does not surrender to bullies,” while blaming the Government’s plans to hand over sovereignty of the Chagos Islands to Mauritius for Argentina “trying their luck”.