The top anti-graft watchdog is taking a series of measures, including punishing its own officials who are easily bribed, strengthening discipline and consolidating its role, amid the ongoing clean-governance campaign.

The Central Commission for Discipline Inspection of the Communist Party of China said anti-graft authorities nationwide should "keep their hands clean" before investigating others.

The commission made the remarks on Thursday while announcing the launch of a campaign to fight corrupt activities at disciplinary authorities' training centers.

It said it will keep a close watch on misbehavior by officials, including the staging of lavish banquets at public expense, entertainment activities and extravagant receptions at training centers.

The commission and provincial anti-graft departments were due to take a thorough look at their training centers before Monday. All corrupt activities at these centers must be ended and any officials responsible for such behavior punished before Sept 10.

Anti-graft authorities have also brought down several disciplinary officials in an effort to tackle corruption.

In the latest case on Wednesday, Yang Senlin, executive vice-secretary of the Shanxi provincial commission for discipline inspection, was investigated by the commission for suspected grave violations of discipline and law.

The commission gave no further details of the case. Reports said Yang used to be a colleague of Jin Daoming, who worked as head of the Shanxi anti-graft watchdog from August 2006 to February 2011.

Jin was investigated by the commission on Feb 27 while serving as vice-director of the Shanxi provincial People's Congress.

At least nine disciplinary officials have been investigated this year. Four are incumbent or former leaders of Shanxi province and two are senior provincial-level officials.

In March, to improve supervision, the commission set up a new office to handle corruption cases involving disciplinary officials.

On May 4, Wei Jian, director of the commission's No 4 disciplinary inspection office, was investigated on allegations of graft. The commission had never previously publicly announced corruption investigations involving its own staff members at director level.

In January, President Xi Jinping urged disciplinary officials to strengthen self-regulation when he attended the commission's annual conference.

Zhou Shuzhen, a professor of clean-governance research at Renmin University of China, said many corrupt officials offered bribes to disciplinary officials, meaning they were unable to investigate corruption cases independently and fairly.

The commission could gain the public's trust by showing its firm determination to punish corrupt disciplinary officials, she said.