Argentina has scrapped a deal with the UK to share any oil found off the Falkland Islands - days ahead of the anniversary of the war for the islands.
Argentina is pushing for talks on the future of the Falklands
Argentina says co-operation with the UK had to be linked to reopening talks over the sovereignty of the islands.
Argentine foreign minister Jorge Taiana said the UK used the deal to justify "illegitimate" claims to the islands.
Monday marks 25 years since the start of the War when UK forces reclaimed the islands after an Argentine invasion.
Scientists estimate that there may be billions of dollars worth of oil under the waters around the Falklands, which are known to Argentina as the Malvinas.
The 1995 agreement between the UK and Argentina is aimed at encouraging oil exploration in the area.
Mr Taiana said Argentina had taken the step after the UK had unilaterally drilled for oil.
He said: "The Argentine decision brings an end...to an instrument the United Kingdom sought to use to justify its illegitimate and unilateral action to explore for resources that belong to Argentines."
Mr Taiana added: "Argentina is not opposed to co-operating with the United Kingdom, but only if this contributes to renewing dialogue over sovereignty."
Since coming to office in 2003, Argentine President Nestor Kirchner has increased calls for the UK to discuss the sovereignty of the islands.
The 72-day war over the South Atlantic islands in 1982 claimed the lives of 255 Britons and 655 Argentines.
Last week, Tony Blair said going to war over the Falklands took "political courage" and had been "the right thing to do".
Argentina claims it inherited the islands from Spain before they were occupied by Britain in 1833.