AN explosion outside the venue for the Rio Olympic opening ceremony was a training drill.

Emergency services detonated a backpack outside the Maracana Stadium on Sunday night while dress rehearsals were taking place for the opening ceremony.

Rio’s bomb squad used a robot to detonate a bag outside gate two of the stadium during a training drill.

Website Brazil Online reported an Inspector Brito, from Rio’s Bomb Squad, as saying the backpack did not contain any explosives when it was detonated by the robot about 9.30pm local time (1030 AEST Monday).

A Rio-based correspondent for the Wall Street Journal, Paul Kiernan, said authorities had confirmed the detonation was a training drill.

“Explosion today at Rio’s Maracana stadium was a training exercise, fire department says,” he tweeted.

Another journalist dismissed initial reports the explosion occurred inside the stadium.

“Pure joke! Stop creating false news! I am journalist here in Brazil and there was nothing in the Maracana today,” tweeted Rafael Leal, a reporter with CBN.

Much of the confusion emanated from a report by the Seven Network, a host broadcaster of the Games, that said a suspicious toolbox had been exploded inside the stadium. That report rapidly spread on social media.

Originally published as Test explosion at main Rio stadium