Mercosur consists of Argentina, Brazil, Paraguay and Uruguay.
Vieira, representing Mercosur's rotating presidency, termed Vietnam an important trading partner for the bloc.
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 agreement aims at boosting trade and investment flows between South America and Southeast Asia.
The talks will discuss expanding trade through phased tariff reductions and elimination, while addressing related non-tariff measures to facilitate market access. Both sides want a framework consistent with World Trade Organisation regulations.
Trade between both sides totalled $11.46 billion in the first eleven months this year, roughly flat year on year (YoY), according to Vietnam’s customs department.
Vietnamese exports to Mercosur rose by 15.9 per cent YoY to $3.59 billion. Imports from the bloc fell by 4.8 per cent YoY to $7.87 billion during the period.
ALCHEMPro News Desk (DS)
Receive daily prices and market insights straight to your inbox. Subscribe to AlchemPro Weekly!