(CNN) -- Argentine President Cristina Fernandez de Kirchner signed a decree Tuesday requiring all ships navigating from Argentina to the disputed Falkland Islands to carry a government permit.
The move comes as tensions over the territory simmer because of British oil companies' efforts to drill off the northern coast of the islands.
The Falklands, known as Las Malvinas in Argentina, lie in the South Atlantic Ocean off the Argentinean coast and have been under British rule since 1833. But Argentina has always claimed sovereignty over them.
The two nations fought a war over the islands in 1982.
Tuesday's decree followed an accusation made last week by the Argentine government that a ship docked on the mainland was preparing to transport tubes to the Falklands for oil and gas exploration.
The decree also creates a special commission that will oversee the application of the new measure.
"It's public knowledge that the United Kingdom has started the search for hydrocarbon resources in the Falkland Islands area," Argentine Cabinet Chief Anibal Fernandez said at a news conference, according to the official Telam news agency.
The Argentine position is that natural resources around the islands should be protected, and Britain must accept international resolutions labeling the Falklands a disputed area.
"This has to do with the defense of the interests of Argentineans, not just about sovereignty," Fernandez said, adding that Argentina lays claim not just to the islands, but to any resources that could be found there.
The Argentines blame "unilateral moves" by the British companies toward exploration as the reason for the recent spat.
"The companies that are planning to explore and exploit gas and oil are going to be met with legal challenges because they are doing it on a continental shelf that Argentina maintains is our own," Argentine congressman Ruperto Godoy told CNN.
CNN's Brian Byrnes and Claudia Dominguez contributed to this report.