A source in Brazilian President Jair Bolsonaro's office confirmed to AFP there had been "various applications" from Venezuelan soldiers, but would not say how many or what ranks.

Brazilian media reported 25 had applied so far.

The petitions for asylum came as Bolsonaro threw his support behind Venezuelans "enslaved by a dictator," a reference to President Nicolas Maduro whom Guaido is challenging for power.

"Brazil is on the side of the people of Venezuela, President Juan Guaido and the freedom of Venezuelans," Bolsonaro said in a series of tweets.

"We support the freedom of this sister nation to finally live a true democracy."

Foreign minister Ernesto Araujo reiterated Brazil's support for a "democratic transition" and expressed "hopes that the Venezuelan military will be part of this process."

Brazil is among more than 50 countries that have recognized Guaido as Venezuela's president.

An apparently carefully planned attempt by Guaido to demonstrate growing military support on Tuesday, however, disintegrated into rioting in the Venezuelan capital, sparking calls for restraint.