His remarks came after Brazilian President Luiz Inacio Lula da Silva and Argentine leader Alberto Fernandez published a joint article saying their aim for greater economic integration included studies of a common South American currency.
Haddad, who floated such a possibility in an article last year, said removing trade barriers between the two largest economies in South America could involve using a single currency for commerce, given a lack of US dollars in Argentina. But that does not spell the end of the Brazilian real, he said.
"Trade is really bad and the problem is precisely the foreign currency, right? So we are trying to find a solution, something in common that could make commerce grow," Haddad told reporters as he arrived in Buenos Aires ahead of Lula's first international trip since his Jan. 1 inauguration.
He said Argentina's trade with Brazil had suffered due to a lack of dollars in the southern neighbor, where an economic crisis has left the government battling to replenish foreign currency reserves, with an inflation rate of nearly 100 percent last year.
Haddad noted Argentina was an important buyer of Brazilian industrial goods and that "several possibilities" were being floated to circumvent its currency problems, though no decision had been made.