Argentina invaded the islands in 1982 but was repulsed by Britain in a 74-day conflict that caused more than 1,000 deaths among combatants and civilians.
Despite an official surrender Argentina revived its claim the islands, which it calls Las Malvinas, were vestiges of British colonialism. To pursue the argument, Argentine President Cristina Fernandez de Kirchner took her campaign to the U.N. decolonization conference but failed to win U.N. agreement to mediate with Britain.
Argentine sovereignty claims gained momentum after the discovery of offshore oil deposits in the South Atlantic's North Falkland Basin.
This week Fernandez made new gains in support won earlier in the Union of South American Nations, or UNASUR, a political group that was led by her husband Nestor Kirchner, who died in October.
UNASUR's 12 member countries agreed in principle to follow Argentina and deny Falklands-bound shipping any facilities at their ports. Ships leaving the Falklands similarly will be denied docking and fuel, UNASUR announced after the leaders met in Guyana.
The heads of state also echoed Argentina's line that vessels flying "the illegal flag of the Malvinas" would be blacklisted and denied access at their countries' ports.
Early reaction from shippers said the ban could cause widespread damage to their business.
Sheila Stewart, assistant general manager of Argos Ltd., told MercoPress the ban would be "very costly" for the fishing company as their crews were picked up in Montevideo, Uruguay, along with supplies.
Stuart Wallace of Fortuna Ltd. was more cautious in his comment. "It is difficult to know what force such a declaration has, if it, for example, requires ratification by the governments involved," he said.
"Of course, if such a policy were to be implemented it would have the unfortunate effect of a significant loss of business for some South American ports. It would inconvenience Falkland vessel owners, but we would deal with any new circumstances.
"Perhaps most importantly, such an aggressive blanket ban would make it clear internationally that we face a tightening blockade aimed at destroying our economy," Wallace told MercoPress.
Adam Cockwell, manager of Work Boat Services Ltd., said, "If all South American ports do decide to block all access to Falkland Islands-flagged vessels then it raises a serious issue for us as we will not be able to go to any ports for our dry docking requirements."
However, he told the news agency, "Day-to-day operations for us would not be seriously affected as we do not regularly go to the coast."