London:
International Olympic Committee (IOC) president Jacques Rogge said London 2012 was a "beautiful example" of what the Olympics should be about, with a Games that breathe life back into a tacky part of a host city.
The International Olympic Committee chief said the regeneration of the "polluted, derelict" quarter of east London at the heart of the Games was a "remarkable" project.
The Belgian said he was confident London would be able to fix the IOC's concerns about transport problems, and insisted the new Olympic Stadium must remain as an athletics venue as 2012 chiefs work out what to do with it later.
"It's a beautiful example of city regeneration and I would say of a positive legacy," Rogge told AFP in London, at the signing of a 10-year sponsorship deal between the IOC and US consumer goods giant Procter and Gamble.
"East London was totally polluted, derelict, and we are going to revive it. We are going to put back a heart, a soul, life, housing and a local population. That's what's remarkable.
"They will revamp it with new access roads, building and social housing. That is a positive legacy of the Games.
"We always demand that there is a legacy which is not purely sporting, with one or two stadiums, but also has an economic, urban and human legacy."
At the IOC's latest check-up on London earlier this month, Olympic chiefs said they were happy with the progress but said their chief concern was the British capital's congested road network.
"It's true that transport in London is difficult because there is lots of traffic but the roads are not very wide," Rogge said.
"But the organisers, along with the city and the public authorities, have come up with a transport plan which, in my opinion, could work well. I'm not worried."
The original Olympic Stadium pledges presented to the IOC in London's 2005 bid had the 80,000-seater venue's top tier removed to leave a 25,000-capacity athletics arena.
But its future is still uncertain, with local English Premier League football side West Ham interested, and other plans for concerts, entertainment use and even cricket have been mooted.
But Rogge was adamant the athletics function would remain. "We insist that they should not leave 'white elephants' and the scale and size of the venues must be really meant at after Games use," the 68-year-old said.
"We are sure that there will be an athletic legacy and another one -- could be football, could be entertainment, could be something different. You can perfectly have a football pitch of highest quality with an athletic track around.
"You can combine both, which in terms of legacy is absolutely perfect, so we have no concerns about that."
The London Games are on schedule and running within their budget of 9.3 billion pounds (14.5 billion dollars, 11.2 billion euros).
"I expect that budget to be on balance," Rogge said.
"We're not speaking about overspending."