Brazil President Dilma Rousseff was joined by the International Olympic Committee President Thomas Bach at a ceremony on Wednesday (5th August) to mark the one-year countdown to the 2016 Olympic Games in Rio de Janeiro.

The countdown to the 2016 Olympic Games in Rio de Janeiro is firmly underway.

Brazil President Dilma Rousseff was joined by the International Olympic Committee President Thomas Bach at an event tha included the Mayor of Rio and Brazil's minister of sports, George Hilton.

Officials unveiled a clock that's counting the hours until the Games.

SOUNDBITE (English) Thomas Bach, International Olympic Committee President:

"We were confident then, and we are confident now, that these Olympic Games will amaze the world."

Following the ceremony, Bach said "there is no imminent, significant risk for the athletes" when asked about a five-month study that showed that Olympic venues are rife with disease-causing viruses and bacteria.

The investigation specifically looked at viruses present in water being used for rowing, sailing and wind surfing, triathlon and open-water swimming.

The tests concluded athletes risk exposure to viruses that could make them too ill to compete.

Demonstrators unhappy with alleged rights abuses by the Games' organisers marched outside of the Rio 2016 Organising Committee building.

The activist group Popular Committee of the World Cup led the protest.