Tensions are high in Rio with bomb disposal experts taking no chances with a suspicious package at the venue set to host the Olympic opening ceremony.

Host broadcaster Channel 7 revealed that a loud explosion had been heard in the famous Maracana Stadium early Sunday evening soon after a robot had been sent in following the detection of a suspicious package.

There were reports the package was a tool box.

"There was definitely an explosion after the robot went in," a Channel Seven spokesman confirmed.


Kitty Chiller in a media conference on Sunday said she is having continued meetings with Rio organisers about security issues including the theft of a laptop and three shirts during a fire evacuation.

"That (the robbery) is concerning," she said, claiming the security presence had since been increased with four private guards on the entrance doors and more noticeable identity checks.

Chiller said all team members had been reminded to keep doors locked and valuables secure.

The Maracana Stadium, which hosted the 1950 World Cup soccer final, will host the Olympic opening and closing ceremonies.