LONDON -- The International Olympic Committee (IOC) gave thumbs up to organisers of the London 2012 Games on Thursday at the end of a three-day visit.

The IOC co-ordination commission chairman Denis Oswald, who headed the 15-strong inspection team to London, gave the local organizing committee LOCOG a mark of 9.75 out of 10 hours after tour to the Olympic Park site.

"Nobody's perfect," Oswald said at a news conference.

The IOC team met British Prime Minister Gordon Brown and new London mayor Boris Johnson when attending a ground-breaking ceremony which marked the start of construction of the main Olympic stadium - three months ahead of schedule.

"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," said the Swiss lawyer.

Accompanied by LOCOG Chairman Sebastian Coe and the IOC's Olympic Games executive director Gilbert Felli, Oswald was full of praises for the 2012 project although he did warn organisers of transport issues.

"This level of detail in the presentations four years before the Games is unprecedented and we have full confidence that we will have an excellent Games.

"I have difficulty in finding any area where we have concerns but if we had to mention something which will be challenging it is traffic and transport.

"But we know plans have been made already and with the quality of people on board we are confident this will be resolved in a satisfactory manner," he said.

Brown pledged that the Games will be delivered on time and on budget, which has been a major controversy as the bill tripled from the original estimated 3.4 billion pounds to 9.3 billion.

He insisted the 500 million pound stadium would not become a white elephant, declaring that 75 pence of every pound will be spent on regenerating the area so that "this stadium, unlike other Olympic stadiums, will be used every day of the year" after the Games.

The bowl of the 80,000-seater stadium can now clearly be seen taking shape at the the 40-acre site which was covered by more than 180 factory and warehouse buildings a year ago. Builders are working towards making sure the project is completed by 2011.

The next IOC commission visit to the capital city is in April 2009.