Argentina is to make its case for sovereignty over the Falkland Islands to other Latin American countries, as tensions over potential oil reserves in the South Atlantic grow.
The country's foreign minister, Jorge Taiana, will ask other countries in a meeting of the Rio Group in Mexico to back his government's claim to control the waters to "Las Islas Malvinas".
The row over the disputed islands has reignited after the discovery of £60bn-worth of gas and oil reserves off the Falklands.
In London, Gordon Brown insisted international law allows British firms to operate freely in the area. Argentina has said their operations violate its sovereignty and announced this week that boats sailing from its ports to the islands would need a permit.
"It is perfectly within our rights to be able to do this. I think the Argentinians actually understand that," said Mr Brown. "Sensible discussions will prevail on this."
The Conservative Foreign Secretary, William Hague, called for "some sort of increased naval presence – it may just be one more ship visiting more regularly in the region. That kind of thing would show very clearly to Argentina – with whom, again, we want friendly relations – that we will be very firm about this. It would send a signal not to misunderstand British intentions.
"One of the things that went wrong in the 1980s is that the Argentines thought we weren't really committed to the Falkland Islands. So we mustn't make that mistake again. Our commitment should be very clear."
A foreign ministry spokesman, Victorio Taccetti, said: "Argentina must think of a long-term strategy. This exploitation is set to take place in Argentine waters, occupied by a usurper. Great Britain will be the first to explore the region, which means that surely there are some previous studies showing there's oil in the area."
Argentina has threatened to stop an oil rig, the Ocean Guardian, which is due to start work in the waters of the Falklands Economic Zone. The UK has warned it will be on international waters and any Argentinian interference would be in breach of international law.Reuse content