Britain warned Argentina that it would "robustly" defend the Falklands if there was a new clash over the sovereignty of the South Atlantic islands.

The warning came after Argentina's foreign minister, who made a protest to the United Nations about Britain's "militarization" of the zone, said the South Atlantic has become "the last refuge of an empire in decline."

"We are not looking to increase the rhetoric. We have not started a war of words," said Britain's UN ambassador Mark Lyall Grant.

"But clearly if there is an attempt to take advantage of the 30th anniversary of the Falklands War by Argentina then we will obviously defend our position and defend it robustly.

"We are responsible for the defence and security of the people of the Falkland islands and they can be reassured that we will carry out that defence in a robust way if necessary, but we have no intention of ratcheting up the rhetoric on this issue," Lyall Grant told reporters.

Argentina's Foreign Minister Hector Timerman earlier gave a press conference at which he justified his protest to UN Secretary General Ban Ki-moon and to the UN Security Council.

Timerman said Britain had increased its military firepower "fourfold" around the Falklands - known as the Malvinas in Spanish - by sending a destroyer and a nuclear submarine.#

British officials have refused to confirm the presence of a nuclear vessel but insist that the warship is just replacing a ship that was already there.

The Argentine minister called for Britain to discuss sovereignty at negotiations and attacked Britain's military power in the South Atlantic, which he said was controlled in London, 14,000 km from the battleground of the 1982 war.

"It is perhaps the last refuge of the declining empire," Timerman said. "It is the last ocean that is controlled from the UK.

Britannia rules only apply in the South Atlantic."

Argentina made its protest to the United Nations amid growing diplomatic tensions around the anniversary of the conflict that erupted after Argentina invaded the Falklands in April 1982.

Britain sent a naval force to reclaim the territory and has since spent heavily to maintain strengthened bases there.

Britain says sovereignty can only be discussed if the Falklands population want it.