Brazil increases military patrols for Rio

A spate of shootings and armed robberies has forced Brazil to boost the number of soldiers on the streets of Rio de Janeiro during the Olympic Games.

Brazil will increase the number of soldiers patrolling the streets of Rio during the Olympics. (AAP)

Brazil will increase the number of soldiers patrolling the streets of Rio de Janeiro during next month's Olympic Games in response to a crime wave, the country's interim defence minister said on Wednesday.

Raul Jungmann said that a rash of armed robberies and deadly shootings on busy thoroughfares in recent weeks had prompted Rio de Janeiro state Governor Francisco Dornelles to ask the military for more help keeping the Olympic and Paralympic Games safe.

More than 21,000 soldiers will assist civil and military police units to protect expressways, the Olympic Village and other Olympic routes in Rio de Janeiro, he said, 3000 more than planned.

Rio has struggled to prepare for the August 5-21 Olympic and September 7-18 Paralympic Games amid a dire financial crisis in the state and one of Brazil's worst recessions ever.

Fears of violent crime have now piled onto existing concerns about terrorist attacks at the Games.

The Zika virus has prompted some athletes to stay home.

And a billion-dollar subway expansion intended to ease circulation at the Games is still not completed.

Dornelles said last week that without more cash the Olympics risked "failure."