Copa, Ipanema off limits after dark

Australia's Olympic athletes must travel incognito in Rio and have been banned from stepping on Copacabana and Ipanema beaches after dark.

The Australian Federal Police have told team bosses of an increase in crime in Rio's landmark areas, prompting reinforced security measures for athletes.

Early on Sunday morning American Ryan Lochte was held up at gunpoint and had his wallet stolen after his taxi was held-up by thieves posing as police officers.

Three other American swimmers were also robbed in the incident.

Australia's chef de mission Kitty Chiller says athletes are not to wear team uniform when they're outside the village not competing and must travel in groups of three.

"We've put the Copacabana and Ipanema beaches, the actual sand, off limits, there's been a lot of increased petty criminal, but criminal, activity on the actual beaches," Chiller said.

Team members must travel by vehicle between 6pm and 6am, even if it's only a few hundred metres.

Chiller said athletes are encouraged to go out in the safer Barra district, around 25km west of Ipanema.

"We've found areas in Barra to go to rather than travelling into town because the Copa-Ipanema area is where the unsavoury activity is happening," Chiller said.

Swimmer Mitch Larkin admitted it was disappointing athletes' movements in Rio were restricted, but agreed safety and security was the priority.

Chiller said there had been no incidents involving Australian team members since two rowing coaches were robbed at knifepoint at Ipanema Beach on the night of the opening ceremony.

She and AOC security chief Greg Nance have been meeting with team leaders as sports finish their competition to reinforce the security protocols.