BEIJING (AFP) - A top Chinese provincial official reportedly linked to former senior party leader Zhou Yongkang has been expelled from the Communist Party, the organisation's internal investigating authority said.

Mr Li Chuncheng was described as "morally degenerate" in a statement released by the ruling party's Central Commission for Discipline Inspection (CCDI) late on Tuesday, which also said he was expelled from his "official position".

Such moves are normally a precursor to a criminal inquiry and China's public prosecutor, the Supreme People's Procuratorate, said on Wednesday on its website that it had opened an investigation into Mr Li.

The developments appear to signal a further tightening of the noose around Mr Zhou, who as a former member of the elite Politburo Standing Committee was one of China's most powerful politicians of the past decade.

China's Communist chief Xi Jinping has been reported in various media to have given the go-ahead for a corruption investigation into Mr Zhou, who headed the country's internal security apparatus until his retirement in 2012.

Mr Li was promoted to mayor of the Sichuan capital Chengdu when Mr Zhou was party chief of the province from 1999 to 2002.

State media reported in 2012 that Mr Li had been dismissed as Sichuan's deputy party secretary for "serious violations of discipline".

His subsequent removal from government signifies that he no longer continues to receive a salary or benefits that officials enjoy.

The CCDI statement said Mr Li had abused his power, took a huge amount of bribes and used his position to help his brother's business prosper.

It also said he had carried out "superstitious activities", without giving details.

The Communist Party authorities have been waging a much-publicised anti-graft campaign since Mr Xi ascended to the leadership 18 months ago.

But critics say no systemic reforms have been introduced to increase transparency to help battle endemic corruption.