Prime Minister David Cameron hit back at Argentina on Thursday over its plans to protest to the United Nations against British militarization of the Falklands, saying islanders would have London's backing for as long as they wished to remain British.

Argentine President Cristina Fernandez, who has accused Britain of militarizing the South Atlantic, hardened her posture on Thursday following stories in the British press about a nuclear submarine being sent to the South Atlantic.

She said her government would make a presentation at the U.N. on Friday denouncing the introduction of nuclear arms in the zone. She did not elaborate.

Foreign Minister Hector Timerman plans to present the complaint to the U.N. Security Council's president.

Britain went to war with Argentina over the Falkland Islands, called Las Malvinas in Argentina, in 1982. London has refused to start talks on sovereignty with Argentina unless the roughly 3,000 islanders want them.

Tensions have risen before the 30th anniversary of the Falklands conflict this year. Oil exploration by British companies off the islands has raised the stakes.

Argentina will find when she goes to the United Nations that it is an absolutely key part of the United Nations charter to support self-determination, Cameron told a news conference after talks with Nordic and Baltic leaders in Stockholm.

The people of the Falkland Islands want to maintain ... their connection to the United Kingdom.

As long as the people in the Falkland Islands want to maintain that status, we will make sure that they do and we will defend the Falkland Islands properly to make sure that is the case, he said in his first comments on Fernandez's pledge.

Britain has denied militarizing the South Atlantic. Asked for reaction to Fernandez's statement on Thursday, a Downing Street spokesman said the government's defensive posture on the islands remains unchanged.

Fernandez has also condemned British plans to deploy one of its most advanced destroyers, HMS Dauntless, to the area. She also criticised the posting of Prince William, second in line to the British throne, to the islands as a military search-and-rescue pilot.

(Additional reporting by Helen Popper and Karina Grazina in Buenos Aires; Stephen Mangen in London; Editing by Jackie Frank and Sandra Maler)