"I would say 9.75, nobody's perfect," Denis Oswald, chairman of the IOC's Coordination Commission, said after being asked to give London's progress a mark out of 10 following tours of the Olympic Park site.

Flanked by London Organising Committee chairman Sebastian Coe and the IOC's Olympic Games executive director Gilbert Felli, Oswald said the 2012 project was bang on course.

"We have seen the shape of the stadium, we have seen something coming out of the ground, it's a good indication that the Games are taking shape," Swiss Oswald, who competed at three Olympics as a rower, said.

Oswald met Prime Minister Gordon Brown and new London mayor Boris Johnson earlier on Thursday when the first construction work on the Olympic Stadium began, three months ahead of schedule.

"The Commission has been greatly impressed by the progress made since our last visit," he said. "The most visible element is obviously venue construction and the progress made on the Olympic Park, in particular, is truly astounding."

Oswald described the level of detail in the various presentations made by LOCOG and its partners during the visit as "unprecedented" although he warned that tougher challenges are ahead, particularly traffic, transportation and security.

"Once the Olympic flag is handed to London in Beijing the focus will be on 2012," he said.

"After that the pressure will move from Beijing to London but we are sure that with the high quality team in LOCOG we will have a fantastic Games for the athletes."

During its visit the commission visited other 2012 venues such as Wembley Stadium and Hyde Park. It also approved moving the fencing venue from the Olympic Park to a nearby exhibition centre.