BEIJING, Sept. 20 (Xinhua) -- China's top securities regulator has approved the initial public offering (IPO) applications of four companies.

The companies -- Shaanxi Beiyuan Chemical Industry Group Co., Ltd., Changzhou Aohong Electronics Co., Ltd., Guangzhou Metro Design & Research Institute Co., Ltd. and Jiangsu Rijiu Optoelectronics Jointstock Co., Ltd. -- will be listed on the A-share market, the China Securities Regulatory Commission said in a statement.

The commission did not specify the total funds to be raised.

The companies and their underwriters will confirm IPO dates and publish their prospectuses following discussions with the stock exchanges.

China is gradually switching from an approval-based IPO system to one based on registration.