The International Olympic Committee has urged London 2012 organisers to get on with their preparations for the Games.
IOC boss Jacques Rogge told BBC Sport that London "is doing OK" but must focus on delivering the Games on time.
"We urge them to work as soon as possible and to prepare today for the unforeseen of tomorrow," said Rogge.
He also said the IOC had "no regrets" about giving the 2008 Games to Beijing despite recent international criticism of China's foreign policy.
Rogge stressed that the Swiss-based IOC was "basically happy" with the progress in London and remained optimistic a permanent tenant for the Olympic stadium will be found.
"That would be something that would please the IOC very much and we are very keen on that," he said.
"We know that Seb Coe and LOCOG (the London Organising Committee of the Olympic Games) are working very hard to find a solution."
The current plan is to reduce the stadium's capacity from 80,000 to 25,000 in 2013 and use it as a multi-sport venue with athletics and community facilities at its heart.
But that plan depends on a football or rugby club becoming an "anchor tenant" to subsidise the stadium. So far that has proved to be beyond Coe and his team, partially because important aspects of the post-2012 plans remain undecided.
Premiership club West Ham have already said they are not interested in moving to Stratford as the capacity is too small, and Leyton Orient are reported to be concerned the capacity is too high.
A spokesman for the Department of Culture, Media and Sport told BBC Sport: "We completely share Jacques Rogge's view that there is not a day to waste as we prepare for the 2012 Games.
"His endorsement of the progress made so far reflects the IOC's very positive comments during their visit to London in June.
"And we whole-heartedly agree with his assessment of the importance of a strong long-term legacy for venues including the Olympic Stadium - which is exactly what we are working towards.
SPORT EDITORS' BLOG"We are committed to venues that both serve our top sportsmen and women and provide lasting benefit for local communities, with long-term 'anchor' users providing stability and security for these facilities."
The shadow recently cast over the preparations for the 2008 Games in Beijing is of a very different nature.
China has been condemned by human rights campaigners for its links with the Sudanese government which is embroiled in a four-year conflict with rebels in Darfur.
China buys two-thirds of Sudan's oil output and is the African state's biggest arms supplier following a 25-fold increase in weapons sales between 2002 and 2005.
International experts say 200,000 people have died and 2.5m have fled their homes in Darfur since the conflict started in 2003.
The Save Darfur Coalition - an umbrella group of 180 religious and human rights groups - has accused China of taking an "ambiguous" stance towards Sudan.
China has also been attacked for its continued support of the military regime in Burma, where recent pro-democracy demonstrations have been crushed.
"The Games will contribute but the Games will not solve all the problems of the world"The Chinese government only agreed to back a critical statement from the United Nations Security Council to Burma when the threat of an Olympic boycott was raised by campaigners.
Rogge said he understood why human rights groups used the Olympics to apply pressure on China, but disagreed with those groups' criticisms of the IOC itself.
"I respect them for what they're doing. It is absolutely legitimate that they get the most from the Olympics," he said.
"But where they make an error is to criticise the IOC for not solving the problems.
"Why would we be able to succeed where generations of heads of state and governments who have come to Beijing have not succeeded? We are a sports organisation - there are limits to what we can do.
"Does that mean that we don't strive for human rights? No, of course we are in favour of human rights, and we've proven that many times in the past.
"But don't expect from the IOC what the IOC cannot do. The Games will contribute but the Games will not solve all the problems of the world.
"We gave the Games to a country that represents of one fifth of mankind. We gave the Games to a country that will change, that is changing. We have no regrets."
Rogge pointed to recent reforms in China's judicial, media and property laws as evidence that the Olympic effect was already being felt. He also praised the emerging superpower for addressing its poor record on child labour.
The 55-year-old, who sailed for Belgium in three Olympics, said he was also satisfied with the steps the Chinese were taking to tackle doping and brushed off concerns about Beijing's air quality.
A recent United Nations report was critical of China's attempts to improve the air quality in Beijing, stating that pollution was three times higher than the level recommended by World Health Organisation standards.
And on Friday, Beijing's weather office warned children and the elderly to stay indoors as heavy fog was exacerbating the city's air quality problems.
An IOC inspection team visited Beijing last week and admitted that pollution remained a concern but said it was confident proposed traffic controls and factory shutdowns would have a positive effect.
Rogge added: "If the atmospheric pollution is too high at certain times then we might consider rescheduling.
"But this is not exceptional for the Olympics. We have a similar situation in the Winter Games with snow. And it's the same with the wind and sailing, rowing or canoeing."
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