Brazilian government leaders and lawmakers have thrown their support behind Argentina in bilateral contacts and international forums but reports after the latest summit talks indicated a hardening of Brasilia's position on the Falklands, a British Overseas Territory Argentina invaded in 1982.
Argentina was beaten back by Britain after a 74-day conflict that led to about 1,000 deaths among Falklands civilians and troops from Argentine and British forces.
Brazilian President Dilma Rousseff and Argentine President Cristina Fernandez de Kirchner met in Brasilia to reassert a position originally adopted by Argentina but increasingly backed by Latin American countries at international political forums.
The Latin American positions on Falklands have tilted toward Argentina especially after British-backed oil exploration companies began prospecting for hydrocarbons in the Falklands waters.
Argentina has also pushed the view that British rule over the Falkland Islands is a vestige of colonialism, a position readily adopted by left-leaning governments or as part of Latin solidarity with neighbor Argentina.
A joint communique after the two leaders' talks declared Brazil's support to "the legitimate rights of the Argentine republic in the sovereignty dispute relative to the Malvinas, South Georgia and South Sandwich islands and its adjoining maritime spaces." Malvinas is the term favored by Argentina for the Falkland Islands.
Latin American declarations over Falklands were seen by analysts as part of an effort to rattle investors who remain optimistic that commercially viable quantities of oil can be found in the Falklands waters to ensure returns on their investments.
Brazil also backed Argentina's historical claim that its forces got to the islands before Britain did in the 1830s, a contention challenged by Britain.
The hardening of Brazilian position means that Falklands shipping has to contend with not only Argentine but also Brazilian ban on access. Falklanders have also faced obstacles in other Latin American countries, causing expensive British operations to keep the islands well-supplied with essential goods.
Britain uses its Falklands bases to train its forces for combat duties in ongoing conflicts, including Afghanistan, and peacekeeping missions elsewhere.
The communique left little doubt that Fernandez received unequivocal Brazilian support for its key position as part of its international campaign against British presence on the islands. Brazil joined Argentina in describing as illegal seafaring vessels flying the Falklands flag and British-backed oil prospecting as a contravention of United Nations resolutions since the 1982 conflict.
Where the latest rhetoric leaves Brazil's relations with Britain remains to be seen. Britain and Brazil in recent contacts pledged close cooperation in military agreements worth several billions of dollars. The two countries signed a defense cooperation treaty last year.