BRASILIA • The Olympic torch was unveiled in the Brazilian capital of Brasilia on Friday, ahead of a marathon journey through the giant Latin American country next year, ending in Rio de Janeiro.

President Dilma Rousseff promised a "historic" Games in August 2016 at an unveiling ceremony, vowing to overcome the country's mounting problems, from massive corruption to street violence.

Officials said the torch - white and inlaid with blue and green waves - will depart from Brasilia in May for a tour of 300 cities and towns across the vast country.

"There will be around 12,000 torch bearers and the flame will travel along approximately 20,000km of Brazilian roads as well as racking up thousands of air miles," the Rio 2016 organising committee estimated.

"The Olympic Torch Relay will conclude on Aug 5, 2016 when the last torch bearer will light the Olympic Cauldron during the opening ceremony, at the Maracana Stadium (in Rio de Janeiro)."

Ms Rousseff - beset by plunging ratings, an expanding corruption scandal centred on state oil firm Petrobras and concerns over security and the environment in Rio during the Olympics - said the Games would show what Brazil can do.

"We are confident that we can meet the challenge before us," she said. "We will show what this country is made of."

AGENCE FRANCE-PRESSE