China on Tuesday named new leaders for its commercial hub Shanghai and the southwestern mega-city of Chongqing, where the disgraced former official Bo Xilai ruled until his downfall earlier this year.

Business-friendly Shanghai Mayor Han Zheng, 58, was promoted to the city's top post as Communist Party chief after serving as mayor since 2003, the official Xinhua news agency said.

Up-and-coming politician Sun Zhengcai, 49, a former minister of agriculture was named top Communist Party official in Chongqing, Xinhua said in a separate report.

Bo is at the centre of the biggest political scandal in China in years, which saw his wife Gu Kailai given a suspended death sentence in August for murdering British businessman Neil Heywood.

He was formally expelled from the ruling Communist Party late last month and is in custody awaiting trial for corruption and abuse of power.

Bo had been tipped for promotion to the top ranks of the party at the once-in-a-decade leadership transition that saw President Hu Jintao hand the top party post to Vice President Xi Jinping last week.

During the reshuffle, Sun was one of the youngest politicians promoted to the 25-member party Politburo, placing him at the forefront of leaders slated to rule China following the next power transition in 2022, analysts said.

Han is credited with guiding Shanghai through the successful World Expo in 2010 and he survived a 2006 corruption scandal which sent former Shanghai party chief Chen Liangyu to jail for 18 years.

A native of Zhejiang province which neighbours Shanghai, Han was educated in Shanghai and served his entire political career in the city.

Several candidates were rumoured to be in line for the Shanghai party chief job, but local government officials were keen to have one of their own take the post instead of an outsider, a Shanghai-based political journalist said.

Sun's promotion is largely based on his expertise in agriculture -- a key sector in a country that needs to feed 1.3 billion people.

He graduated from Beijing Agriculture University in 1987 and later spent a year as a visiting scholar at Britain's Rothamsted Experimental Station, an agricultural research centre based at a manor house in Hertfordshire.

Later he served as minister of agriculture for three years.

Following Bo's dismissal from Chongqing in April, the sprawling city of 30 million people has been run by Vice Premier Zhang Dejiang, who was last week promoted to the elite seven-member Politburo Standing Committee.

Zhang is slated to become China's next parliamentary head in March next year.