A key ally of China's former security czar Zhou Yongkang has resigned from his seat on the country's parliament, the National People's Congress (NPC), ahead of annual sessions which begin next week, state media reported on Friday.
Li Dongsheng, a former vice-minister for public security, is already under investigation by the ruling Chinese Communist Party's disciplinary body for "suspected serious law and discipline violations."
China's parliament has accepted Li's resignation as a member of parliament for the southwestern province of Sichuan, the official Xinhua news agency reported.
The move is significant because it removes immunity from prosecution extended to NPC delegates, who rarely challenge the party line.
Speculation has been mounting for months that the authorities may be getting ready to charge Zhou, a former member of the party's elite Politburo Standing Committee, with abuse of power.
A corruption investigation begun last year has widened to cover Zhou's family and powerful political allies and business connections in the country's energy sector, reports indicate.
Zhou, former political mentor to jailed former Chongqing party chief Bo Xilai, stepped down from his post as Politburo standing committee member and Commission chief in November 2012, where he wielded huge power, political analysts say. His post has since been downgraded to report to the committee.
Pin Ho, editor of New York-based Chinese news magazine Mingjing News, who has been following the probe in detail, told RFA that it has now widened to include more than 100 people in his circle of influence.
Most of those helping party investigators with their inquiries are high-ranking officials and business executives, Ho quoted his own inside sources as saying.
Most of the suspects are being held in the Yangtze river port city of Yichang in central Hubei province, Ho said.
And the five investigation teams of more than 100 personnel already assigned to the case are getting ready to detain more people, in a case that has further-reaching consequences than the Bo Xilai scandal, he said.
"Now, it's just a question of when this will be formally announced via the media," Ho said.
"I have three separate sources, one of which is saying that this affair will continue to drag out without an announcement, while the other two sources are saying that it will be announced before the start of the NPC [next Wednesday]."
"These two sources are saying that there will definitely be an announcement," he added.
Ho said higher ranking government and most Party officials had largely been informed of the progress of the probe.
Suspects in the probe come from a tangled and often informal network of power and influence headed by Zhou, including the state-run petroleum industry, Sichuan provincial government, the nationwide Communist Party political and legal affairs committees, as well as land and resources bureau and propaganda officials, Ho said.
Four of Zhou former political secretaries have been detained for investigation to date.
Reported by Hai Nan for RFA's Cantonese Service. Translated and written in English by Luisetta Mudie.