Gordon Brown has visited Shanghai on the second day of his trip to China.
Gordon Brown and Premier Wen Jiabao have agreed to boost trade
The prime minister has been focusing on green issues - visiting a "clean" power station outside Beijing before heading to Shanghai to see a new "eco-city".
The Taiyang Gong power station, fuelled by natural gas instead of coal, is the first of its kind in China and has been developed with the help of a UK firm.
Mr Brown earlier became the first VIP visitor to see inside Beijing's "bird's nest" Olympic stadium.
'Greatest Olympics ever'
Standing alongside Britain's double gold medallist Kelly Holmes, he said: "This is going to be one of the greatest Olympic games ever.
He added that he was "thrilled" that British designers had been involved in its development.
"I thought it was magnificent and it is going to be great for the athletes, it's going to be great for the public," he said.
Asked if he thought pollution would cause problems for athletes, he said: "I think today is a wonderful day, although there is some smog when people come to Beijing they will see this magnificent stadium and this magnificent effort by the Chinese people to make one of the greatest games in history."
Mr Brown, who has received an official invitation to the Olympics in the summer, said: "I'm looking forward to being here at the games in August."
Mr Brown also visited a Shanghai sports hall to watch disabled soccer players take part in a training session.
After visiting Taiyang Gong power station - developed with the help of British company Camco and which will become fully operational in November - the prime minister flew to Shanghai on the second leg of his three-day visit.
He headed for talks with local politicians and will go to visit the Dongtan eco-city project outside the city.
Mr Brown, on his first visit to the country as prime minister, had earlier said there was a "huge opportunity" for British businesses in China.
He said trade was not "one way" - while Britain would import more goods, it would export its financial services.
He and Chinese premier Wen Jiabao have agreed to boost trade by 50% by 2010. Mr Brown has also offered China £50m to help the country tackle climate change.
Opposition leaders have urged the PM to raise the issue of human rights.
Foreign Secretary David Miliband rejected suggestions the prime minister was giving China an "easy ride".
He told BBC Radio 4's Today programme: "I think it is important that politics and political development is part of the discussion that we have with China but obviously there is a range of other issues - the economy, the environment and the reform of international institutions."
After China, Mr Brown heads to India where he will announce plans to train 750,000 English teachers there over the next five years.