FILE - Sun Zhengcai, party secretary of Chongqing attends a meeting on the side line of the National People's Congress in Beijing, China.
FILE - Sun Zhengcai, party secretary of Chongqing attends a meeting on the side line of the National People's Congress in Beijing, China.

A Chinese politician considered a potential future leader has been replaced as head of the central mega-city of Chongqing amid reports he is facing a graft investigation.

The move is a possible sign of a shakeup in roles ahead of a crucial Communist Party congress later this year.

The South China Morning Post said Monday that Sun Zhengcai is being investigated by the ruling Communist Party's anti-graft arm.

The Chongqing government said on its website Saturday that Sun Zhengcai was being replaced as head of the city's Communist Party committee by Chen Min-er.

Both Sun and Chen sit on the party's 25-member Politburo and are considered candidates for promotion to the body's Standing Committee, the apex of political power in China. 

The Chongqing announcement gave no details on the move.