Zhou Yongkang trial marks high point in graft fight, but can Xi Jinping keep up the pace?

Bringing the powerful ex-security chief Zhou Yongkang to trial marks a high point in President Xi Jinping's war against corruption but questions remain about whether he can build on the momentum.

China watchers and experts said it was difficult to predict whether Xi would go after another "tiger" of Zhou's stature or someone even bigger. Ling Jihua - the right-hand man of former president Hu Jintao - is under investigation but yet to be charged. But Ling never reached the top echelon of politics.

While there is strong public support for the investigation into Zhou, some worry that too many shocks to the system might split the Communist Party and undermine its foundations.

"The situation is too complicated now," said Zhang Ming, a professor of political science at Renmin University. "The extent of corruption in China is too wide and too deep."

Beijing-based political commentator Zhang Lifan shared the concern, saying "it remains to be seen if the top leadership will stop after Zhou or take down even bigger tigers".

Publicly, Xi has repeatedly vowed on various occasions that the campaign will continue, stressing the need to root out factions within the party. His top commander in the war against corruption - Wang Qishan - has said there would be no "forbidden zones" in the fight against graft.

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All this suggests the campaign will not stop soon. On the day the prosecution against Zhou was announced, the Central Commission for Discipline Inspection (CCDI) disclosed the total cases of public money spent on extravagant official banquets in February. It said the figure had risen by 30 per cent compared with a month ago, indicating that there were still decadent elements within the party.

This is a clear sign the CCDI intends to maintain pressure and solicit public support to intensify the anti-graft drive.

Also yesterday, the PLA Daily - the official mouthpiece of the military - published a commentary urging the army to push forward with the fight. The commentary noted that many military officers "are still flouting the law" and "believe they can escape the punishment". It warned that the armed forces needed to keep up the pressure and restore discipline.

This came just a month after the death of disgraced former general Xu Caihou - the most senior military official to be investigated and indicted for corruption in recent decades.

Xu was accused of taking advantage of his position to help others gain promotions. In return, he allegedly accepted huge bribes personally and through his family. He was expelled from the party in June and was to face a court martial. After his death, military prosecutors decided to drop the charges against him and said they would continue to process his illicit financial gains in accordance with the law.

Last month, the army announced that 14 senior officers, many of them major generals, had also come under investigation. Among them were Guo Zhenggang , son of Xu's senior counterpart, Guo Boxiong . Speculation about Guo - who was the de facto leader of the PLA for a decade - has swirled on the mainland. The general's fate will be closely watched and may give some signal as to just how far Xi's anti-corruption campaign will go.

Additional reporting by Angela Meng and Jing Li