BEIJING -- Discipline inspection agencies of the Communist Party of China (CPC) at various levels have been introducing more effective measures to regulate and oversee their staff.

A total of 22 officials with the Central Commission for Discipline Inspection (CCDI), the CPC's top anti-graft agency, have been investigated and about 230 officials received written or oral warnings since the 18th CPC National Congress in late 2012, according to CCDI sources.

During the same period, more than 10,000 officials with discipline inspection agencies at various levels were punished. Among them were in-service and retired officials.

"We would like to deliver a clear message that discipline inspection agencies will not relax scrutiny over themselves," the sources said.

The agencies have also paid great attention to education and training of their staff. About 178,000 officials attended more than 1,000 training courses in the past five years.

Jointly with China Central Television, the CCDI produced a three-episode TV documentary, which featured interviews with former officials of discipline inspection agencies convicted of graft.

The documentary, aired in January last year, served as a fresh warning to all inspection officials.

To streamline anti-graft work, the CCDI issued a protocol regulating the procedure of how discipline inspectors initiate and carry out investigation and put it in a trial run in January last year.

The protocol aimed to close loopholes in inspection procedures and minimize the possibility of outside intervention and rent seeking.

"The protocol well responds to the question who to inspect discipline inspectors," said Professor Xie Chuntao with the CPC Central Committee Party School, adding that internal control measures were carefully designed and learned lessons from corrupt officials.