LEAD: Argentina to complain to UN Security Council over Falklands Eds: Releads with British reaction; adds London dateline

Buenos Aires/London (dpa) - The British government rejected Argentinian claims Wednesday that it was "militarizing" the long-running conflict over the Falkland Islands by despatching a Royal Navy destroyer to the South Atlantic.

The latest war of words between London and Buenos Aires was sparked by the announcement by Argentinian President Christina Fernandez de Kirchner that her government would complain about the issue to the UN Security Council in New York.

"I have instructed our foreign minister to make a formal complaint to the United Nations Security Council and Assembly about this militarization of the South Atlantic," she said late Tuesday.

In London, a spokeswoman for Prime Minister David Cameron said it was a matter for Argentina what issues it wished to raise at the UN.

"The people of the Falklands choose to be British. Their right to self-determination is a principle enshrined in the UN charter," she added.

However, the spokeswoman rejected the Argentinian accusation that Britain was creating a risk to international security by "militarizing" the dispute over the islands.

"We are not militarizing the South Atlantic. Our defensive posture in the Falklands remains the same," said the spokeswoman.

She confirmed that the government had contingency plans in place in "case of aggressive actions towards the self-governing British overseas territory."

A spokesman for Britain‘s Foreign Office had made clear earlier that Britain had no intention of entering into negotiations over the sovereignty of the Falkland Islands.

"The people of the Falkland Islands are British out of choice. They are free to determine their own future and there will be no negotiations with Argentina over sovereignty unless the islanders wish it."

The disputed area includes the Falkland Islands, called Islas Malvinas in Spanish, which have been British territory since 1833 but are claimed by Argentina.

A two-month conflict in 1982 between the two countries over the islands, which lie around 450 kilometres off the Argentinian coast, left about 1,000 dead from both sides.

Britain said late January that it would deploy the HMS Dauntless, a latest-generation air defence destroyer, to the Falklands. The move, to take place in the next two months, was a routine manoeuvre to relieve a frigate, authorities said.

Tensions have been rising ahead of the 30th anniversary of the failed invasion by Argentine forces, in April.

Kirchner also spoke out against a posting by Britain‘s Prince William, the grandson of Queen Elizabeth and second in line to the throne, who arrived in the Falklands Saturday as part of his training as an Air Force search-and-rescue helicopter pilot.

The Argentinian president said she would have preferred William to travel to the islands "in civilian clothes and not a military uniform."

Recent oil discoveries in the islands have also contributed to the tensions. "The great battles of the 21st century will be over the large natural resources of developing countries," Kirchner said. dpa ip rg aet jg cds lns Authors: Juan Garff, Anna Tomforde