Security noose around the Falkland Islands was tightened by Argentina with a tough new warning to Australian oil explorer Billiton to stay out of the controversial hydrocarbon prospecting operations in the Falklands, which it claims are under British occupation.

Warning Britain and the Falklands administration that it will not abandon its claim of sovereignty over the islands, Argentina has built up its military presence in the Falklands' waters.

British troops prevailed over an Argentine invasion force in the war over the islands in 1982 but Buenos Aires never abandoned its claim over the islands.

The Argentine campaign for "return" of the Falklands to Argentina gained momentum last year after a British oil prospecting firm unveiled plans for extensive drilling of the basin.

Believed to be the world's largest after Saudi Arabia's reserves, Desire Petrolum and Falklands Oil and Gas, backed by the British and Falklands governments, announced they would go ahead with plans to exploit the Falklands' hydrocarbon resources.

The renewed row over the Falklands' ownership is speculated as a precursor to a new military conflict by British media. Argentina has been canvassing for international sympathy and last week won Latin American support at the Cancun summit of Central and South American leaders. U. N. intervention is also canvassed for by Buenos Aires in a bid to halt oil prospecting.

U. S. officials have said the Obama administration will remain neutral on the Falklands and will not be drawn into the dispute. (With Inputs from Agencies)