Chinese authorities have vowed to crack down on judicial corruption in commutations of sentences and probation following a number of cases of convicts bribing their way out of jail.

"Terms and procedures on commutation, parole and serving a sentence outside jail for medical reasons should be stringent within the framework of the law," said an instructive document released on Monday by the Commission for Political and Legal Affairs of the Communist Party of China Central Committee.

In one high-profile case, Zhang Hai, former board chairman of Jianlibao Group Co. Ltd., a Chinese beverage giant, used illegal means to have his sentence cut by five years in a second court trial and had his jail term further reduced by more than four years while he was serving the sentence.

Police officers, prison and court officials were involved in these commutations, and Zhang escaped overseas after he was freed.

While confirming the valid role of remission in rehabilitating convicts and helping them return to society, the commission noted "some problems" in this area that "severely trample the sanctity of law and harm the credibility of law enforcement," citing criminals who use money and power to dodge punishment.

According to the commission, illegally making decisions to commute a sentence or grant release on probation will be severely punished.

The document focuses on regulating commutation, parole and serving a sentence outside jail for medical reasons for three kinds of crimes, namely taking advantage of one's position, disrupting financial order and financial fraud, and organizing mafia-style groups.

In order to warrant remission, criminals convicted of these three crimes should be proactive in disgorging ill-gotten gains, assisting in recovering illicit money and goods overseas or paying compensation, it said.

Those who try to reduce their sentences or secure probation using personal influence or other improper means will be refused remission even if they are repentant, according to the document.