China’s top anti-corruption official said on Monday that the purge of former Politburo member Bo Xilai was a warning to corrupt officials that they would be “relentlessly pursued” irrespective of their influence.

Underscoring the scale of the government’s corruption problem ahead of its leadership transition, He Guoqiang, who heads the Communist Party of China’s (CPC) powerful Central Commission for Discipline Inspection, said the CPC had punished as many as 660,000 officials in the past five years alone for a range of disciplinary violations.

Mr. He, a member of the Politburo Standing Committee, the nine-member ruling body that will step down at the November 8 Party Congress, called on anti-corruption bodies to “promote the combat against corruption and to build a clean party and government”, the official Xinhua news agency reported.

Mr. He highlighted the case of Mr. Bo, who was expelled from the CPC on September 28, as reflecting the CPC’s desire to “relentlessly pursue” officials who violated party discipline. “The corrupt ones, no matter who are involved, will be relentlessly followed and will never be given a chance of escaping punishment in accordance with Party discipline and the law,” Mr. He said.

Mr. Bo was sacked as Chongqing Party Secretary in March after his former right-hand man caused a scandal by fleeing to a United States Consulate in Chengdu with evidence of the role of Mr. Bo’s wife, Gu Kailai, in the murder of British businessman Neil Heywood.

Many Chinese analysts, however, see Mr. Bo’s fall as having as much to do with internal power struggles as corruption. Mr. Bo, who was accused by Party authorities of taking bribes in earlier stints in Liaoning province and committing other abuses of power, was widely seen as a front-runner for a seat on the next Standing Committee before the Heywood scandal. Mr. Bo was promoted to the 25-member Politburo in 2007. That he was allowed to rise to the highest levels of the party, despite the long list of misdemeanours investigators claimed to have unearthed over many years, triggered renewed questions in the media about the absence of effective oversight within the Party.

Many scholars have called for more independence for anti-corruption bodies and for courts, which are controlled by the Party, to improve supervision. Most corruption cases are handled internally by the Party and not sent to the courts for criminal prosecution. Of the 640,000 cases investigated last year, only 24,000 officials were transferred to the judicial system for suspected crimes, according to Xinhua.

Mr. He said some “improvements” had been made on coordination between different agencies to prevent officials from fleeing to foreign countries with ill-gotten wealth. Earlier this year, Chinese media reported that a top official in the Ministry of Railways had stashed $ 2.8 billion in overseas accounts.

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