BEIJING, Dec. 2 -- China's top securities regulator on Monday unveiled and put into effect rules to allow early shareholders of a company to sell their shares during an initial public offering (IPO).

The temporary regulation is one of the important supporting measures in China's newly announced IPO reform plan, according to the China Securities Regulatory Commission (CSRC).

Company shareholders who have held shares for more than 36 months are eligible to sell shares to investors during the company's IPO, but the sales must not lead to a change of the company's controller or major changes in its ownership structure.

The move will help raise the number of shares for sale during the IPO and promote adequate seller-buyer interactions to curb high prices set for IPOs, the CSRC said.

On Saturday, the commission issued a plan for reforming the country's IPO system, which vowed to be market-oriented and law-based and aimed at maintaining market fairness and protecting investor interests.