The government of the Falkland Islands is concerned about a decision by a United Nations commission to expand Argentina's maritime territory.
It has sought clarification from Britain over the possible implications of the ruling, which Argentina claims will increase its waters in the South Atlantic Ocean by 35%, or 0.66 million miles, to include the Falkland Islands and beyond.
The commission's ruling 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.
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.
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".