Hanoi, Dec. 21 -- The Southern Common Market (Mercosur) and Vietnam have launched negotiations for a preferential trade agreement, Brazilian Foreign Minister Mauro Vieira announced at the bloc's 67th summit in Foz de Iguazu on December 20. Mercosur comprises Argentina, Brazil, Paraguay, and Uruguay. Vieira, representing Mercosur's rotating presidency, described Vietnam as an important trading partner for the South American bloc. Argentina, Brazil, Paraguay, and Uruguay issued a joint statement with Vietnam confirming the formal start of negotiations. The parties are finalising terms of reference that will define the scope, structure, and methodology for talks, according to a statement posted on the Brazilian government's website. The agre...