Britain and Argentina on Monday marked 30 years since the invasion of the Falkland Islands triggered a 74-day war, with diplomatic tensions still running high.

In a statement to mark the anniversary, Prime Minister David Cameron described the invasion as a "profound wrong" and reaffirmed his government's commitment to upholding the right of Falkland islanders to determine their own future.

"Thirty years ago today the people of the Falkland Islands suffered an act of aggression that sought to rob them of their freedom and their way of life," Cameron said.

The brief but bloody war ended in defeat for Argentina, costing the lives of 649 of its troops, after Britain sent a task force to the islands to reclaim the territory which it has ruled since 1833.

Britain lost 255 servicemen in the hostilities and three local Falkland islanders also died.

But the human toll has in recent years been overshadowed by fresh Argentine claims of sovereignty and a battle to exploit offshore oil deposits.

Argentine President Cristina Kirchner, who has denounced British rule of the islands as an "anachronism", will unveil a monument and eternal flame to the country's dead servicemen in the southern city of Ushuaia.

Ushuaia, where commemorations began Sunday, is in Tierra del Fuego province, the closest Argentine territory to the Falklands, and Kirchner will deliver a speech there to veterans of the conflict.

In Britain, there will be a remembrance ceremony at the National Memorial Arboretum in Alrewas, eastern England, where a "Falklands flame" will be lit for 74 days.

The Falklands -- population around 3,000 -- are located some 400 nautical miles from Argentina, which calls the islands the Malvinas.

The April 2, 1982 invasion ordered by the then-ruling military junta in Argentina caught the Foreign Office off guard and initially there was skepticism on whether military action in the far-off territory was worthwhile.

Then prime minister Margaret Thatcher, however, resolutely vowed to reclaim the islands and once the war was won she basked in her reputation as "The Iron Lady," to win re-election in 1983, and again in 1987.

Tensions between London and Buenos Aires have flared anew since 2010, when Britain authorized oil companies to explore in Falklands waters, and Argentina has accused Britain of militarising the seas around the windswept islands, taking its claims to the United Nations.

The island's oil reserves, which remain untapped until now but which analysts predict could be worth tens of billions of dollars, have been a major bone of contention between the two countries since their discovery in 1998.

London is today facing a united Latin American front led by Brazil -- the region's dominant power that displaced Britain in December as the world's sixth largest economy -- over Argentina's territorial claims.

During the conflict, Chile -- then under the rule of the late Augusto Pinochet -- gave covert support to Britain, and the only regional country to provide true aid to Argentina was Peru, which sent weapons and Mirage jets.

Latin American countries now depend more on each other and are less dependent on Europe and the United States as they seek to assert a common identity.