Beijing 2008 Olympics organisers are on track to stage "great Games" the International Olympic Committee said on Wednesday, as the Chinese were to mark the 100-day countdown to the opening ceremony with festivities.

Beijing has completed construction of its 31 venues and is staging a series of test events to try out venue operations ahead of the August 8-24 Olympics. Other infrastructure works including a new airport terminal and subway lines will further improve the city's operations.

"The Beijing Organising Committee has put a tremendous amount of effort into putting on great Games for the athletes," the IOC said in a statement.

"It is currently fine-tuning its operations and we are satisfied by the assurances that we have received across a number of areas of Games preparations, ranging from media service levels to environmental contingency plans for improved air quality."

Beijing has pumped in a total of about $40 billion to stage the Games and the IOC is eager to see the Games succeed in tapping into one fifth of the world's population.

"The 100 days ahead will bring mounting excitement and energy to Beijing. Citizens and visitors will see the city continue to transform itself, as it welcomes athletes, the media and spectators for the final test events, as well as for the Games themselves," the IOC said.