GB medals have swayed the sceptics says Boris

He claimed scepticism, particularly over the £9.3 billion budget, was slowly ebbing away.

Team GB has won 17 gold medals so far in what has turned out to be Britain's most successful Olympics since 1908.

The Mayor told reporters: "The amazing success of Team GB is completely blowing away the Olympo-scepticism of large chunks of the public and it's a wonderful thing to behold.

"These Games are changing public perception of the Olympics. I've just come in from London and I can tell you that the city is in a state of excitement."

He admitted many Londoners still feared the budget would increase further.

"We are being asked to deliver the Games during a credit crunch and a downturn and possible recession. We seek economies wherever we can find them and that's exactly what we're doing," he said.

But he insisted that he would not impose a "mean, penny-pinching austerity" on the Games and the capital would still end up with a fantastic show.

He said cutting costs while at the same time guaranteeing a meaningful legacy posed a "dilemma and difficulty".

Mr Johnson said he was not intimidated by the success of the Beijing Olympics and insisted London could hold its own.

"We have been dazzled, we have been impressed, we have been blown away by these Games but we have not been intimidated. In our own sweet way without wasting taxpayers' money I'm sure that we can do just as well in 2012," he said. Mr Johnson admitted he had not raised China's human rights record in his meetings with Beijing officials - saying the Games was not the right time or place.

"I think millions of people in Britain are deeply concerned about human rights in China but I feel very strongly that these Games offer a fantastic opportunity for China to open to the rest of the world," he said. "I certainly don't think you can overlook human rights abuses."

The Mayor had earlier arrived in China looking tired and dishevelled after a cattleclass flight from London.

British Airways denied the Mayor an upgrade from his economy seat on the nine-hour overnight flight to the Olympics.

City Hall aides requested a move to business class for the Mayor before leaving Heathrow but were turned down. A spokesman for British Airways refused to comment on the request but it is certain to be viewed as a snub by mayoral aides who were convinced their boss would be treated like a VIP.

Mr Johnson said later: "I travelled very, very comfortably in World Traveller. We were attended by every possible comfort and I have no regrets. I neither sought nor, am I sad to say, was I offered an upgrade. In fact I was explicitly refused one."

Mr Johnson will have a key role in the closing ceremony on Sunday when he receives the Olympic flag from his Beijing counterpart.