| Argentina and Britain fought a brief war in 1982 over the disputed Falkland Islands [EPA]
Argentina, Brazil and Uruguay have agreed to close their ports to ships flying the flag of the Falkland Islands, a British territory in the South Atlantic claimed by Argentina.
The move was announced on Tuesday at a meeting of the Mercusor trading bloc in the Uruguayan capital Montevideo.
Leaders of the bloc, which also includes landlocked Paraguay, agreed that Falklands-flagged ships "should not dock in Mercosur ports, and if that were to happen, they should not be accepted in another Mercosur port," said Uruguayan President Jose Mujica.
A statement issued at the end of the summit said member countries would adopt "all measures that can be put in place to impede the entry to its ports of ships that fly the illegal flag of the Malvinas Islands," referring to the islands by their Argentine name.
Argentine President Cristina Kirchner de Fernandez, who took over the presidency of the trade bloc from Mujica, thanked her fellow presidents for the show of support for Buenos Aires' claim to the archipelago, which lies 400 nautical miles from the Argentine coast.
"I want to thank everyone for their immense solidarity with the Malvinas," Kirchner said in a speech to the summit. "But you should know that when you are signing something on the Malvinas in favour of Argentina you are also doing it in your own defence."
Malvinas 'a global cause'
"Malvinas is not an Argentine cause, it is a global cause, because in the Malvinas they are taking our oil and fishing resources," she said. "And when there is need for more resources those who are strong are going to look for them wherever and however they can."
Britain has claimed the Falklands since 1833 and the two countries fought a brief war in 1982 after an invasion by Argentine forces, and maintains a small military presence there.
The islands, which have a population of about 2,500 people, are currently a self-governing British territory and both the British government and the Falklands government maintain that sovereignty is not a matter for discussion.
The Falkland Islands government "hopes for peaceful co-existence between Argentina and the Falkland Islands, without diluting or adapting the position on sovereignty," according to the islands' website.
But the dispute has heated up again as British companies have begun exploring for oil in waters surrounding the islands.
In mid-September, UK-based Rockhopper Exploration announced that it hoped to begin oil production in the region in early 2016, ramping up to a maximum output of 120,000 barrels per day by 2018.
Mujica announced last week that his country would bar Falklands ships from Uruguayan ports, prompting Britain to call in the Uruguayan ambassador to express its concern.