A former close colleague of China's ex-chief of internal security Zhou Yongkang has been sacked for "suspected severe violations of disciplines", state media said Thursday, stepping up anti-corruption inquiries another notch.

Li Chongxi was dismissed as chairman of the Sichuan province Political Consultative Conference -- a debating chamber that is part of the Communist Party-controlled governmental structure -- for "suspected severe violations of disciplines", the official Xinhua news agency said.

The phrase is commonly used as a euphemism for corruption.

Authorities were investigating "according to the procedure", Xinhua added, but gave no further details.

It cited a statement from the ruling party's powerful Organisation Department, which has no website apart from one that receives allegations of officials' wrongdoings.

Li, 62, was the chief secretary of Sichuan's party apparatus when Zhou was the Communist number one in the province from 1999 to 2002, according to the two officials' biographies on state-run news portals cpc.people.com.cn and xinhuanet.cn.

Li was promoted to be the vice party chief of the province in 2002, before he took other posts and then his current position, which is at the ministerial level, this year.

Authorities had announced the investigation into him at the weekend.

He has become at least the 19th official at vice-ministerial level or above to fall since a once-in-a-decade power transition in November last year that anointed Xi Jinping as the ruling party's general secretary.

Among the 19 at least five are believed to have been proteges of Zhou, who is a former member of the all-powerful Politburo Standing Committee (PSC) and one of China's strongest politicians of the past decade.

The New York Times last month cited "sources with elite political ties" as saying that Xi has given the go-ahead for a corruption investigation into Zhou himself.

It would be the first time in decades that such a high-ranking figure has been targeted in a formal inquiry, which would send shockwaves through China's elite. PSC members have generally been regarded as untouchable even after retirement.

Xi, who became head of state in March, has warned that corruption could destroy the party and vowed to crack down on high-ranking officials, described as "tigers", along with low-level "flies".

High-profile cases that have emerged over the past year include the sacking of Jiang Jiemin, head of China's state-owned assets watchdog, and Li Dongsheng, formerly a vice minister of public security.

On Thursday Tong Mingqian, a senior official in the central province of Hunan, was sacked over a vote-buying scandal that ensnared more than 500 local and provincial officials.

Tong was expelled from the Communist Party and removed from office for "serious discipline and law violations", the Communist Party's Central Commission for Discipline Inspection said in a statement on its website.

Critics say no systemic reforms have been introduced to increase transparency to help fight endemic graft.