Two leaders of a gambling and prostitution ring have been sentenced to life in prison and another 85 others were given jail sentences after a nightclub - involving 300 million yuan ($45.8 million) of illicit money - was busted in Zhengzhou, Henan province.

Zhang Liyong, president of the High People's Court in Henan province, announced the result of the case when he delivered an annual work report to the provincial People's Congress.

More than 2,900 women had provided sex services at Royal No 1 Nightclub in Zhengzhou before it was raided and forced to close in November 2013, according to his report.

A total of 152 policemen have been punished for covering up the ring, and more than 8 million yuan in bribes were seized, according to a recent report by People's Police News, which is run by the Public Security Ministry.

Three prosecutors were also found guilty, the report said.

"The case is, in essence, systemic corruption," said Wang Jingbo, a law professor at China University of Political Science and Law.

"When the entire political environment in an area is polluted, the police team is very much likely to be involved in corruption. There is always a huge benefit behind such corruption. The policemen are not immune from the temptation of money."

Zhou Tingxin, former deputy police chief in Zhengzhou, was the most senior police officer punished in the case.

Zhou was found "borrowing" money from the club, which is a disguise for taking bribes from the ring. Other police officers were either awarded stock shares in the club or given a certain amount of money monthly.

Wang said public power was misused by policemen for personal gain. "Their powers have been transformed into a means of making money," he said.

"An integrity supervision mechanism should be put in place outside the jurisdiction of a police department. And it must be a regular means to prevent unethical behavior," Wang said.