David Cameron has dismissed Argentina's claims to the waters surrounding the Falkland Islands as "speculation", vowing to defend the islander's rights.
A United Nations commission has recommended that Argentina's maritime territory should be expanded across the South Atlantic Ocean by 35 per cent, or 0.66 million miles, a move which would encompass the Falkland Islands and beyond.
The government of the Falkland Islands has sought reassurances from the British government.
The decision by the UN Commission on the Limits of the Continental Shelf could have significant consequences for Buenos Aires' claim to natural resources in the sea around the disputed island chain.
A spokesman for David Cameron said: "One of the commissions has looked at issues regarding maritime territory. We have yet to receive details of that report. This is an advisory committee that makes recommendations that are not legally binding. It does not have jurisdiction over sovereignty issues.
"I don't think we should get ahead of ourselves. Speculation of what the report says has come from Argentina so we should wait to see what comes out of the commission.
"What is important is what the Falkland Islanders think. They have been clear that they want to remain an overseas territory of Britain and we will continue to support their right."
The commission's recommendation follows a 2009 report by Argentina that fixed its territory 200 to 350 miles from its coast, surrounding the archipelago that it calls the Malvinas.
Oil exploration is already pumping millions of pounds into the Falkland Islands economy. Many islanders remain concerned about Argentina's claim as well as the potential for problems from rapid change brought by the new industry.
The Falkland Islands are internally self-governing, but Britain is responsible for their defence and foreign affairs and came to their aid during an invasion by Argentina in 1982.
The British government says islanders cannot be forced to accept Argentine sovereignty against their will.
Mike Summers, chairman of the Legislative Assembly of the Falkland Islands, said: "Our understanding has always been that the UN would not make any determination on applications for continental shelf extension in areas where there are competing claims."
The UN commission's finding included the caveat that there is an unresolved diplomatic dispute between Argentina and Britain over the islands.
Argentina's foreign minister Susana Malcorra said the "historic" decision "reaffirms our sovereignty rights over the resources of our continental shelf".
The Telegraph/ UK
The Telegraph/ UK