The UK has hit back at Argentina's threats of court action over Falkland Islands oil exploration, calling its behaviour "illegal intimidation".
Foreign minister Hector Timmerman had threatened legal action against firms drilling off the UK territory, over which Argentina claims sovereignty.
But the UK Foreign Office said it was a legitimate commercial venture.
Prime Minister David Cameron said Britain would "continue to protect and defend" the islands.
In threatening legal action against oil prospectors, Mr Timmerman had told reporters: "The gas and oil that is found in the South Atlantic belongs to the Argentinian people.
"All these companies are entering illegal territory."
He warned that legal action would target oil companies as well as firms providing them with financial and logistic support.
It was the latest in a series of measures taken in recent months by Argentina to assert its claim to sovereignty over the Falklands, which it calls the Malvinas.
Mr Timmerman said companies involved in oil exploration in Falklands waters were "violating UN resolutions" calling for talks on sovereignty.
The UK Foreign Office said the right to develop the hydrocarbon sector was an "integral part" of the Falkland islanders' right to self-determination.
"These latest attempts to damage the economic livelihoods of the Falkland Islands people regrettably reflect a pattern of behaviour by the Argentine government," the Foreign Office said.
"From harassing Falklands shipping to threatening the islanders' air links with Chile, Argentina's efforts to intimidate the Falklands are illegal, unbecoming and wholly counter-productive," it added
Several British companies are searching for oil and gas in Falklands waters.
One of them - Rockhopper - says it has found significant reserves and is seeking investment partners to begin production.
The search for oil has inflamed tension over the disputed islands ahead of the 30th anniversary of the Falklands War.
On 2 April 1982 Argentina invaded the Falklands, only to be defeated by a British task force sent to recover them.
The UK says there will be no negotiations on sovereignty as long as the Falkland islanders wish to remain British.
Mr Cameron said: "The people of the Falkland Islands could not be clearer that they want to continue their status as an overseas territory of the United Kingdom.
"As long as they want that, that is not going to change."