Brazilian President Dilma Rousseff has guaranteed the country's airports will cope with increased demand during the football World Cup.

The South American nation is expected to welcome more than 600,000 international visitors during the June 12-July 13 tournament.

Rousseff's comments followed admissions by the government that military airports could be used due to unfinished work at terminals in several World Cup host cities.

"All those traveling through our airports in most capital cities today will find that the dust and the noise are receding, and the fencing is being removed to make room for modern, comfortable facilities," Rousseff told state news service Agencia Brasil.

"They will be used for the World Cup, but they are chiefly made for the convenience of (domestic) passengers, of these millions of Brazilians who can now afford to travel by plane. I can ensure that our airports are ready for the World Cup. We'll give all (visitors) a proper welcome."

The government and local organizers have been given a boost by news that the new Terminal 3 at Sao Paulo's Guarulhos International airport will open on Tuesday.

The facility will handle up to 12 million passengers a year, accommodating up to 34 aircraft at any given time.

According to the government, Rio's Galeao airport has increased capacity by 80% while Manaus's maximum passenger load has tripled.

Expansion works at airports in Brasilia and Belo Horizonte are on track to be completed by the end of the month, Rousseff added.

In addition to airport expansions in Brazil's state capitals, Rousseff has also announced that 1.5 billion U.S. dollars will be invested in regional terminals.

"The local airports will make passenger flows easier, so that travelers living or working far from the major centers will gradually be able to take off from within 100 kilometers of their current location," Rousseff said.

"We have already completed feasibility studies for 163 airports, and moved on to the design and engineering phase."