The south American nation is feared to be increasing military expenditure, according to reports. Senior ministers in the country have also made a series of increasingly aggressive statements about the islands in recent years.

A Whitehall source told the Sun newspaper: “The Defence Secretary’s decision reflects our operational judgments and the heightened nature of the threat.”

A spokesman for the Ministry of Defence added: “There is a defence review and an announcement will be made about it. There will be a full statement by Michael Fallon.”

Military analysts have previously argued that without an aircraft carrier, Harrier jump jets or the ability to deploy a task force, the islands could be seen as an easy target for Argentina.

Buenos Aires has intensified its claim since oil exploration began. In 2011 its president, Cristina Fernández de Kirchner, called David Cameron “arrogant” for insisting the islands will remain British as long as their inhabitants wish to.

British oil company Rockhopper Exploration revealed significant discoveries of oil, which it says are enough oil to make the Falklands a significant production centre. 

Arturo Puricelli, Argentina’s defence minister, previously declared that British vessels were “contaminating” the south Atlantic and pledged to fight for the Falkland Islands, known in Argentina as the “Islas Malvinas”.

Speaking on state TV, Puricelli said: “We don’t want [the British] to come here to make this unnecessary show of military strength. We have no doubt at all that we are going to recover our Malvinas islands. The international community will support us.”

The British government last year rejected calls to sit down with Argentina to negotiate sovereignty over the islands.

The 24-nation Decolonisation Committee passed a resolution calling on Britain and Argentina to negotiate a solution to the dispute over the south Atlantic archipelago, essentially favouring Argentina’s stance in the two-century old dispute. 

“The UK’s position on the UN’s decolonisation process is well-known. We regret that the UN Decolonisation Committee continues with its outdated approach,” said a Foreign Office spokesman at the time.