Tips from the public have been an increasingly important resource in the crackdown on corruption since the 18th National Congress of the Communist Party of China (CPC) in 2012, as they will be carefully handled by disciplinary watchdog authorities through five working procedures, observers said.

After a tip against an official is made, the case will go through preliminary verification, case filing and investigation before ending in a punishment, the CPC Central Commission for Discipline Inspection (CCDI) said on its official website on Sunday.

The CCDI began to receiving tips on its app since last June, in addition to the traditional reporting methods, including email, telephone and CCDI website.

In 2015, the CCDI website and its mobile app received 128,000 reports, up by 13 percent from 2014, according to data released by the CCDI.

Verification groups - consisting of at least two disciplinary officials - will collect information by talking with the official's acquaintances, usually his or her superiors, without the official's knowledge. The official will also be questioned if the tip is found unreliable following initial talks, according to Zhuang Deshui, deputy director of the Research Center for Government Integrity-Building at Peking University.

"It is important to win support from the officials' superiors," Zhuang told the Global Times, while suggesting that superiors be kept in the dark when it comes to serious cases to prevent a collusion.

If preliminary verification already finds conclusive evidence of the offense, the official can be put under shuanggui, literally, "double-designation," referring to a procedure in which officials are obliged to "confess" to wrongdoings, Zhuang noted.

Such verifications require the approval of the CCDI standing committee, while the verification of cases involving top-level officials will require approvals after the Political Bureau of the Central Committee of the CPC meets, reported the China Economic Weekly, a magazine affiliated with the People's Daily.

The Political Bureau approved the verification of the case of Chen Liangyu, former secretary of the CPC Shanghai Committee and a former member of the Political Bureau. Chen was sentenced to 18 years in prison for accepting bribes and abusing power in 2008, the magazine added.

During the case-filing or investigation phases, more officials will be involved when prosecutors and police officers are engaged, Zhuang said. "But there is a strict avoidance system, which bans all people linked to the official under investigation from participating in the process. Fellow townsmen will also be forbidden from participating."

"Disciplinary authorities are better empowered to combat corruption under the system and the judicial authority's independence is fully respected when unlawful activities will be placed under its jurisdiction," he said, adding that more regulations should be placed to better clarify the different roles during the investigation.