CHINESE President Xi Jinping's flagship anti-corruption drive claimed its most powerful scalp yet at the weekend with the arrest of former security chief Zhou Yongkang.

Mr Zhou, who retired from high office in 2012, is the first former member of the politburo standing committee to be arrested in the anti-corruption clampdown and the highest-ranking Chinese politician to be arrested since former party general secretary Zhao Ziyang in 1989.

The Supreme People's Procuratorate - the country's top criminal investigator - said on Saturday that he had been arrested while prosecutors investigate a number of suspected crimes. On the same day the Communist Party announced that it had expelled him from its ranks.

The party's Central Commission for Discipline Inspection says it has found evidence that Mr Zhou "took advantage of his posts to seek profits and accepted huge bribes personally and through his family."

The former secretary of the Central Political and Legal Affairs Commission, which directs party policy on the police and courts system, was also charged with leaking state secrets.

He is also accused of abusing his power to help mistresses and friends amass fortunes at the expense of the state and "trading his power for sex and money."

Although adultery is not a crime in China, it is regarded as a breach of party discipline when committed by senior officials because it can expose them to blackmail and increase the risk they will be induced into corrupt behaviour.

The party cited Mr Zhou's love affairs as the reason for his expulsion, saying the criminal charges would need to proceed through official courts.

The arrest was hailed by Communist Party newspaper People's Daily as evidence that Mr Xi was fulfilling his promise to tackle corruption among "tigers" - officials of the highest rank - as well as among less powerful "flies."

It showed "nothing is off-limits" and that everyone was equal before the law, the paper claimed.

But Beijing historian Zhang Lifan said the decision to charge such a senior politician could also be intended to "shock and awe" opponents of the anti-corruption drive.

Chinese tabloid paper the Global Times noted approvingly that it would increase the "terror" felt by corrupt officials.