"Of course I am worried. A person whose slogan is to break the relationship with Brazil that was built over centuries does worry us. It would worry anyone," Haddad said in an interview with Reuters late on Wednesday.

Milei, dubbed "Argentina's Bolsonaro" due to his ideological affinity with Brazil's former hard right president, has said in campaign speeches that he would limit trade with Brazil if elected.

He has called Brazilian President Luiz Inacio Lula da Silva an "angry communist" and a "socialist with a totalitarian vocation" and stated that Argentina would "follow its own path" regarding its membership of the South American common market Mercosur.

Argentina, despite its serious economic crisis, remains the top market for Brazilian manufactured goods, and has sought Brazilian assistance on issues such as financing imports.

Haddad said the Brazilian government worked on four proposals that provided guarantees for Brazil to accept financing imports by Argentina, but none of them managed to go ahead due to the impossibility or inability of the neighboring government to comply with demands.

The Brazilian proposals continue to stand, Haddad said, adding that depending on who is elected relations with Argentina may become impossible.

Argentine voters go to the polls on Sunday and Milei is the front-runner but it is not certain he can win outright or have to face a second-round run-off in November.