The investigation of a high-ranking Chinese state-owned oil company boss for corruption may indicate that the country's former security chief is also under probe, analysts said on Monday.
A variety of political factors lie behind the reports, which come hard on the heels of the high profile trial of Bo Xilai, the former ruling Chinese Communist Party chief for Chongqing megacity, they said.
State media said on Monday that Party discipline inspectors are currently investigating former China National Petroleum Corp (CNPC) boss Jiang Jiemin, the highest-ranking official to be caught in a crackdown under the new leadership of President Xi Jinping.
Jiang is being investigated for "alleged graft" linked to oilfield contracts and "ill-gotten payouts" while he was chairman of CNPC, the country's biggest oil producer, the China Daily reported.
The news comes amid unconfirmed reports that investigators are also probing the affairs of former security chief Zhou Yongkang, who is also a former CNPC chief and is widely seen as Bo Xilai's political mentor.
Zhou—who retired from the all-powerful Politburo standing committee in a leadership transition last November—is the most senior official to be investigated in China for decades, the Hong Kong-based South China Morning Post reported last week, quoting unnamed Beijing sources.
The Post's report added fuel to speculation that the authorities would target Zhou once Bo's trial, which ended last week, was out of the way.
Zhou headed CNPC from 1996 to 1998, before being appointed Party secretary of the southwestern province of Sichuan from 1999 to 2002.
While most analysts have dismissed wild rumors of a coup plot between Zhou and Bo last year, many believe Zhou had been grooming Bo to take over his own position at the head of the political and legal affairs committee in Beijing during the leadership transition in November.
Bo's widely expected place on the Politburo standing committee would have ensured that Zhou's interests wouldn't be damaged by his retirement, had Bo not been removed from his post at the start of a corruption and murder scandal which was to shake the Party to its core, political analysts say.
Former CNPC chief Jiang, meanwhile, had been widely tipped to take over as director of the national resources committee under China's cabinet, the State Council, prior to his investigation.
Analysts said that Zhou and Jiang had moved in the same circles.
"CNPC was previously regarded as part of Zhou Yongkang's network of influence," Beijing-based political analyst Chen Yongmiao said.
"If they are hoping to take down a tiger the size of Zhou Yongkang, then ... they will definitely have to go after people on either side of him," Chen said, in a reference to President Xi's metaphor for high-ranking corrupt officials.
He said the move against Jiang has little to do with a desire on Beijing's part to "clean up" the oil industry.
"It's not that they want to grab control of these resources; it's that they want to clean up Zhou Yongkang's network of power and influence," Chen said.
Professor Xia Ming, political science lecturer at the College of Staten Island in New York, agreed.
"More and more information is pointing towards Zhou Yongkang," he said. "The Bo Xilai ... case got deeper and deeper throughout the trial, and this will definitely implicate Zhou Yongkang more and more."
Transcripts of Bo's trial produced by the court revealed a reference to his "superiors," which was edited out before being retweeted in a later edition, according to foreign media covering the trial.
Xia said Zhou's position had likely been weakened by the number of people he had harmed on his rise to power.
"He hurt a lot of people, and there is no one left in a key position who can protect him now that he has retired," Xia said.
Beijing-based investigative journalist Zhu Ruifeng, who runs the whistle-blowing website Supervision by the People, said the impetus for the current anti-graft campaign appears to stem from Party disciplinary chief Wang Qishan.
"I think the new leadership, in particular Wang Qishan ... wants to show that they're really doing something," Zhu said.
"So you could say there is some determination to battle corruption."
But Chen said the campaign will likely have the opposite effect.
"The more they clean things up, the more corrupt the newly promoted officials become," he said. "They are just putting on a show for the public."
"They want ordinary people to have a sense of hope."
President Xi has that warned corruption could destroy the Party, and has threatened to expose high-ranking officials, or "tigers", along with low-level "flies."
However, political analysts say that officials with friends in the right places are unlikely to be touched by the crackdown, and reports suggest many are liquidating their assets and moving overseas.
China scored poorly in an annual global corruption index published last year by Transparency International, ranking 80th out of 176 countries, down five places from the previous year.
Reported by Grace Kei Lai-see for RFA's Cantonese Service, and by Yang Jiadai for the Mandarin Service. Translated and written in English by Luisetta Mudie.