BEIJING -- Stock exchanges should conduct supervision over listed firms more proactively, the country's securities watchdog said Saturday.

It is the responsibility of stock exchanges to be supervising IPOs, mergers and the reorganization and delisting of listed firms, according to Liu Shiyu, head of the China Securities Regulatory Commission (CSRC).

"All players are subject to the supervision of stock exchanges, not only members and listed firms, but also involved intermediary institutions such as accounting firms," Liu told a general meeting of the Shenzhen Stock Exchange.

Compared with administrative supervision and self-discipline, Liu pointed out that stock exchanges have the advantages of offering more comprehensive and effective supervision.

"Stock exchanges should punish market irregularities without mercy," Liu added.

The CSRC has been toughening supervision and punishment of illegal market activities such as insider trading and stock manipulation after the market rout in 2015 shattered investor confidence.

Last month, the CSRC slapped a 3.47 billion yuan fine on a company chairman for stock market manipulation, a record high.