Forwards Gabriel Jesus and Roberto Firmino scored either side of halftime at Estádio Mineirão.

Jesus registered the opener in the 19th minute when he side-footed home a low cross from Firmino.

A Firmino tap-in midway through the second half sealed victory after good work from Jesus.

Argentina captain Lionel Messi felt a number of decisions had not gone his team's way.

He was particularly aggrieved a penalty had not been awarded by Ecuadorian referee Roddy Zambrano prior to Brazil's second goal.

"Brazil were not better than us," Messi was reported as saying by BBC Sport.

"They found the net early and the second goal came from a penalty they didn't award.

"The officiating was crazy.

"There were clear penalties, on (Nicolas) Otamendi, on Kun (Sergio Agüero).

"He (the referee) was on their side.

"In every divided ball or dispute, he went their way."

Agüero hit the bar with a header in the first half and Messi struck a post 11 minutes after the restart for Argentina, who have not beaten Brazil in a major competitive fixture since 2005.

The result ensures Messi remains without a major title with Argentina, his only success being a gold medal at the Beijing 2008 Olympic Games. 

“We knew that it would be difficult because of the players they have," Brazil’s Casemiro was reported as saying by The Guardian.

"It’s about details. 

"We knew it would be scrappy and that there would be wind-ups and time wasting. 

"But we have to congratulate our strikers who did a great job. 

"When they got chances, they scored."

The second semi-final, between Chile and Peru, is due to take place tomorrow in Porto Alegre.

The winner of that will face Brazil in the final in Rio de Janeiro on Sunday (July 7).

The loser will meet Argentina in the third-place playoff in São Paulo on Saturday (July 6).