An 56-year-old Chinese man has begun a bid to swim 1,200 kilometres (750 miles) down the polluted Yangtze River to visit the World Expo in Shanghai, state media reported Thursday.

China Telecom employee Bao Zhengbing began realising what he said was a childhood dream to swim from his home in Wuhan in central China to Shanghai on Wednesday, the Xinmin Evening News reported on its website.

"Now at last, I'll swim all the way to Shanghai, to fulfil my own dream and to see the World Expo," Bao was quoted as saying in the Shanghai Daily before starting his journey.

"When I was 12, I travelled to Shanghai by ship. The beautiful landscapes along the way impressed me so much that I wished one day I could swim along the route and stop wherever I chose," he said.

Bao may however find China's longest river has changed since he was a boy. Experts have warned the river is considered "cancerous" and that industrial pollution is killing it, according to state media.

Bao acknowledged the adventure was dangerous and signed a statement saying he took full personal responsibility for anything that happened to him before beginning his swim, Xinmin Daily reported.

Friends travelling in a boat and by car will follow him during his 35-day journey, during which he plans to swim 40 kilometres a day, reports said.

The 2008 Beijing Olympics inspired similar physical feats as Chinese showed their national pride, including a 97-year-old grandmother who rode 2,400 kilometres on a tricycle to see China's badminton team.