RIO DE JANEIRO (AFP) - Angry rowers blasted choppy conditions at the Olympic regatta on Saturday (Aug 6) as waves helped capsize Serbia's men's pair on the opening day of Rio 2016.

Serbian duo Milos Vasic and Nenad Bedik saw their Olympic dream turned upside down as they flipped over in the heats.

The pair were capsized by foaming currents at the Rodrigo de Freitas Lagoon near Copacabana beach and failed to get back in their boat to finish the race.

Vasic and Bedik were handed a reprieve by world rowing's governing body Fisa allowed them to move into the next round.

"Fisa Executive Committee has decided to allow the SRB M2- to compete in the next round of racing following the DNF in H3, M2-," world rowing posted on their official Twitter account.

However, they were far from the only rowers affected with Australia's Kimberly Brennan describing the course as unfit for purpose.

"I've been speaking to a lot of rowers in the boat park and there's a lot of discontent," said Brennan, who qualified in third in her heat of the women's single sculls.

"I was pretty close to sinking out there, which would generally be an indication that the course isn't rowable."

Zimbabwean Micheen Barbara Thornycroft said conditions were "probably the worst I've ever raced in."

"It was chaotic. It was anyone's game, whoever could get their blades in and move. I was seeing everyone catching crabs and tipping," she said.

Egypt's Nadia Negm was another to narrowly escape capsizing.

"It was intense. Halfway through the course this huge wave just went into my boat. It went all the way up to my face. I mean, I'm lucky I didn't tip over.

"I've never really raced in water like this. This was a new extreme, but it's good experience."