The market slump on Monday was partly triggered by fears that a six-month ban on share sales by listed companies' major shareholders, imposed during the height of a market rout last year, will expire on Jan. 8, unlocking an estimated 1.24 trillion yuan (130 billion pounds) worth of shares.

Most of the 30 companies which announced extensions of the share sale ban were privately-run firms, according to the newspaper.

They include Zhejiang Century Huatong Group Co Ltd (>> Zhejiang Century Huatong Automotive Part), Shandong Sun Paper Industry Co Ltd (>> Shan Dong Sun Paper Industry JSC Ltd), Zheijiang Sanhua Co Ltd (>> Zhejiang Sanhua Co., Ltd.) and Changshu Tianyin Electromechanical Co Ltd (>> Changshu Tianyin Electromechanical). ($1 = 6.5184 yuan)

(Reporting by Samuel Shen and John Ruwitch; Editing by Eric Meijer)