The Royal Navy has abandoned major warship patrols of the Falkland Islands because of ship shortages.

Despite an official policy to patrol the South Atlantic, a major British warship has not visited the area for almost seven years, leaving the islands’ defence to a small patrol vessel and four RAF Typhoons, the Telegraph understands.

Rishi Sunak is facing calls to review the Falklands’ security after the new Argentinian government announced plans to buy fighter jets, submarines and warships, raising fears that Argentina could launch a fresh invasion in a “repeat of 1982”.

The area around the Falklands was previously patrolled by a frigate or destroyer with anti-ship and air defence missiles, but Navy bosses have downgraded the islands’ naval protection to HMS Forth, an offshore patrol vessel with one 30mm cannon. Four Typhoon fighter jets remain on the island, but one is not operational.

Defence sources told the Telegraph that the last major warship to be deployed was the Type 23 frigate HMS Portland in 2017.

A Navy source said: “Everything only stretches so far, and we only have so many frigates and destroyers. If things were to hot up, we would look at it again.”

On Jan 15, the Ministry of Defence (MoD) revealed that four of the Navy’s 11 frigates are currently out of operational duty, including two that will be scrapped because of a staffing crisis.

New Type 31 and Type 26 frigates are not expected to enter service until at least 2027 and 2028, respectively. A new destroyer, the Type 83, is scheduled to launch in the late 2030s.

Javier Milei, the new Argentinian president, has said that his country has “non-negotiable” sovereignty over the Falklands and pledged to force the British Government to release its claim through “diplomatic channels”. The Foreign Office has rebuffed his efforts.

Since taking office last month, Mr Milei has reportedly approved a US-backed deal to acquire 24 F-16 fighter jets from Denmark, and has launched a review into plans to buy three submarines and a stock of warships from France or Germany.

The US Congress approved the sale of the F-16 jets in October, and has privately pushed for Mr Milei’s government to choose the American-made Lockheed Martin planes over JF-17 jets manufactured in China.

Victoria Villarruel, Mr Milei’s vice president and the daughter of a prisoner of war in the Falklands, has announced the government will triple its defence budget by 2032 to make the armed forces “fundamental institutions of the country”.

Argentina does not currently have any operational fighter jets, after decommissioning its 1970s Mirage III fleet in 2015, while its navy has operated without a submarine since the sinking of ARA San Juan on a training exercise in 2017.

However, the plans to restore Argentina’s armed forces prompted calls for Britain to resume major warship patrols.

A spokesman for the Friends of the British Overseas Territories, a charity that supports the Falklands, warned that the UK had “a reduced presence, a less capable Royal Navy and a lack of vision in defending against Argentina’s growing and modernised armed forces”.

“We urge the UK’s Ministry of Defence to rethink defences and overseas territory capabilities before security is compromised and we are forced into a larger conflict,” the spokesman told The Telegraph, adding: “We do not want to see a repeat of 1982.”

The UK has stationed around 1,200 military and civilian personnel on the Falkland Islands, and operates an RAF base at Mount Pleasant and nearby naval port for HMS Forth. The British Army has three Sky Sabre surface-to-air missile batteries there.

A 2016 plan to station two RAF Chinook helicopters at the Falklands was abandoned, with defence bosses deciding after a year to redeploy the helicopters elsewhere.

Following the Falklands War, the RAF stationed nine F-4 Phantom fighter jets on the island, reduced to four in 1988. The jets have since been replaced three times, first with the Tornado, then with two variants of the Typhoon.

The Telegraph understands one of the RAF’s four Typhoon jets stationed on the islands is currently non-operational, while civilian helicopters on the island are not equipped for combat. The Falklands are periodically visited by HMS Protector, an ice patrol ship that conducts scientific research and does not carry any weapons.

‘Invasion highly unlikely’

Lord West, who was awarded a Distinguished Service Cross for his service in the Falklands War, said an invasion of the islands was “highly unlikely at the moment” but called for the MoD to ensure it has “sufficient defence assets in the Falklands to show that if anyone did anything stupid, that they would have some assets that they would have to overcome”.

“It’s something we have to keep an eye on all the time, because no matter how we might kid ourselves, they think that the Falkland Islands are theirs, and they’re not,” he said.

John Healey, the shadow defence secretary, added that ministers must not “treat the Islands as out of sight, out of mind”.

“Our Armed Forces have a core task in defence of the Falklands, as well as a crucial role in South Atlantic environmental and fisheries protection and life critical evacuation options,” he said.

In response to a recent parliamentary question on the Falklands, James Heappey, the minister for armed forces, said: “The Ministry of Defence undertakes regular assessments of the requirements for defence support to the Falkland Islands.

“I am satisfied that the military presence in the South Atlantic is at the appropriate level to ensure the defence of the Islands.”

An MoD source said: “The Defence Secretary is adamant that the Falklands are British and that is not open to negotiation.

“The islanders have voted overwhelmingly to remain British and we will always defend their rights to self-determination.”