Police cordon off beach volleyball area

Police cordoned off a large area around the Beach Volleyball Arena in Copacabana and deployed robotic bomb detection devices on Friday while the Rio Olympics opening ceremony was being staged at Maracana Stadium.

Armed police and the military were seen beginning to seal off an area of Avenida Atlantica, which runs in front of Copacabana beach, where the 12,000 capacity temporary beach volleyball venue is erected, at around 8.40pm local time (9.40am Saturday AEST).

The robotic bomb detection devices were deployed around 10 minutes later and examined what appeared to be a black bag and a red rucksack.

Half an hour later a member of the bomb disposal team was seen examining the packages with the cordon still in place.

Earlier thousands of anti-government protesters marched along Rio's Copacabana on Friday - just hours before the ceremony.