By Ben Blanchard and Benjamin Kang Lim
BEIJING (Reuters) - Few figures are as divisive in China as former domestic security tsar Zhou Yongkang, reportedly under investigation by the ruling Communist Party for corruption.
Even the once ambitious but now ousted politician Bo Xilai, whose trial on corruption ended last week, doesn't evoke the same depth of feeling that Zhou does.
From the oil fields of frigid northeastern China, the hulking Zhou worked his way up to the elite Politburo Standing Committee, where his spending on domestic security exceeded the budgets for defense, healthcare or education.
"In the Party, he is credited with (ensuring) stability and preventing its collapse," a source with ties to the leadership told Reuters, requesting anonymity to avoid repercussions for discussing China's secretive politics.
Counters prominent dissident Hu Jia: "He was out of control. Nobody could touch him."
Hu was convicted on subversion charges in 2008 for a series of essays that, among other things, called for Zhou to be sent to the gallows for alleged human rights abuses.
Zhou, who formally retired earlier this year, is facing a corruption probe, Hong Kong's South China Morning Post newspaper reported on Friday.
The government has declined to comment on the report while Zhou could not be reached. Reuters has not been able to independently verify the article.
But Chinese authorities are going after proteges of Zhou at energy giant China National Petroleum Corporation (CNPC). Zhou rose through the ranks of the oil sector to become general manager of CNPC in the mid-1990s.
On Sunday the government announced that Jiang Jiemin, chairman of CNPC until March, was being investigated for "serious discipline violations", shorthand generally used to describe graft. Jiang currently heads the regulator responsible for state-owned enterprises.
Four other CNPC officials are also being investigated, the government said last week.
Any move against Zhou could be unprecedented since no sitting or retired Standing Committee member has been jailed for economic crimes since the Communists swept to power in 1949.
"Zhou Yongkang I think is clearly in trouble. Exactly what (for), I don't know, but people have said to me that he's finished," said Tony Saich, a China expert at the Harvard Kennedy School of Government.
PARTY GIVES HIGH MARKS FOR PERFORMANCE
Born in Jiangsu province near Shanghai during the height of Japan's invasion of China in 1942, Zhou joined the Party while still a student at the Beijing Petroleum Institute.
After years in the oil industry and related ministries, Zhou ran the huge southwestern province of Sichuan, before being named public security minister in 2002 and then in 2007 taking the law and order portfolio in the Politburo Standing Committee, China's ruling inner core.
The central leadership was impressed by Zhou's performance overseeing security, despite a massive rise in unrest and protests fuelled by frustration at a yawning wealth gap, pollution, land grabs and official corruption.
He Guoqiang, once head of the party's powerful Organisation Department which oversees personnel decisions, called Zhou "clear-minded, innovative, bold and focused" in 2002. Li Yuanchao, He's successor, said in 2007 that public security during Zhou's tenure was "one of the best in history".
"Zhou Yongkang's contribution was not small," said the source with ties to the leadership.
Zhou once cautioned that China's development required order, saying that preserving stability was the government's "number one duty".
That earned him the enmity of China's small but determined human rights community, as he pursued anyone he thought could undermine stability, including the banned spiritual movement Falun Gong and activists such as Nobel Peace Prize laureate Liu Xiaobo, jailed during Zhou's tenure in 2009.
"Zhou must accept a great deal of responsibility for the complete lack of progress on legal issues over the past 10 or 20 years. Indeed, things went backwards," said dissident artist Ai Weiwei, detained without charge in April 2011 for 81 days.
TROUBLE STARTED WITH BO XILAI
Zhou, now 70, maintained close contacts with the oil industry even after rising to the top of the party.
In recent years he also played a role in coordinating and pushing through agreements on gas supplies from Central Asian neighbors including Turkmenistan and Kazakhstan.
"Zhou has all along been watching the industry, paying attention，and giving his support from a higher government level," said an oil industry official, speaking on condition of anonymity.
While Zhou's allies at CNPC are under scrutiny, some other key figures remain in senior positions, including Fu Chengyu, chairman of Asia's largest refiner Sinopec Corp.
Zhou's troubles began last year.
He was implicated in rumors that he hesitated in moving against Bo Xilai, once the high-flying party boss of the city of Chongqing, who was ousted in the wake of a scandal in which his wife was convicted of murdering a British businessman who had been a family friend.
Before Bo's downfall, Zhou had recommended that Bo succeed him as domestic security chief, multiple sources with direct knowledge of the matter or ties to the leadership have said.
The domestic security forces Zhou ran also suffered a humiliating failure last year when blind rights advocate Chen Guangcheng was able to escape from 19 months of house arrest and flee to the U.S. embassy in Beijing.
Such fumbles gave then-president Hu Jintao and his successor, President Xi Jinping, a shared motive to put a growing array of police forces and domestic security services under firmer oversight.
When Zhou stepped down along with most members of the Standing Committee at the 18th Party Congress last November, the position he occupied was downgraded.
His successor Meng Jianzhu was only made a member of the Politburo, the 25-member body which reports to the Standing Committee.
(Additional reporting by Chen Aizhu, John Ruwitch in SHANGHAI and Irene Liu in HONG KONG. Editing by Dean Yates)