Brazilian security forces conducted the training session on Saturday at a Rio de Janeiro train station, with the drill including a mock bomb attack on the train system and a shooting.

During the simulated counter-terrorism operation, two "terrorists" in a parked train set off an explosion and fired blank rounds. Soldiers soon arrived to contain the "attack," followed by members of special forces arriving in two helicopters who "neutralized" the perpetrators.

The drill, supervised by a central command, took place in the Deodoro train station in the north of the city, with Deodor being one of four main venues of the Summer Olympics, set to begin on August 5.

"The exercise was very useful, because it allowed us to work within real parameters for the operation and utilization of the troops," said General Mauro Sinott, who heads the military's counterterrorism unit.

Vamped-up security

The drill comes as concerns about security in the city, notorious for crime and violence, have been heightened still further by the deadly truck attack in the French city of Nice on July 14. The exercise was planned before that date, but Brazil said on Friday it was bolstering security for the August 5-21 Olympics following the attack in Nice which killed 84 people and left scores badly wounded.

French military officers testifying to a parliamentary inquiry commission on the terror attacks in Paris and elsewhere in France in 2015 have said that the country has received information of a planned terror attack on its team at the Olympics. But Brazilian Defense Minister Raul Jungmann has said that he had not been alerted to such a threat by French authorities.

Last month, the Brazilian intelligence agecy ABIN intercepted messages in Portuguese that it said were linked to the extremist "Islamic State" (IS) group, which claimed the attack in Nice.

'Safest place in the world"

Despite reports of threats to security and worries in some quarters that Brazilian security forces might not be up to the job, US Olympic authorities recently said they were satisfied that the Games would be kept safe.

"I fell like the safest place in the world is going to be the village and the competition venues, so I think our athletes wil be among the safest people in Rio because of all the security around them," said United States Olympic Committee chief executive officer Scott Blackmun.

Brazil plans to mobilize some 85,000 members of the security forces as of July 24 to protect the 10,500 athletes, officials and journalists attending the Games, as well as the 500,000 visitors coming from across the world to experience the event. The central command in charge of security will include experts from 106 countries.

tj/jm (AFP,dpa)