TWO stock exchanges on the Chinese mainland have taken a major step to boost the stock market by easing restrictions on the purchase of shares during the "corporate result seasons."

The "window period" during which major shareholders are barred from increasing stakes in their companies, ahead of the release of financial results, has been reduced to 10 days from 30 days, the Shanghai Stock Exchange and Shenzhen Stock Exchange said on their Websites.

The stock exchanges also scrapped a rule which banned major shareholders from increasing stakes 10 days ahead of the release of "preliminary reports" of companies.

"The move indicated the government's resolution to save the market," said Wen Lijun, an analyst of Nanjing Securities Co Ltd.

"With strong support from the central government, the Shanghai Composite Index could reach 2,500 points soon and investors can focus on stocks in centrally administrated state-owned enterprises and conduct short-term trading," Wen told the reporters.

The revised rule follows a package of measures announced by the central government recently to bolster the ailing stock markets, including scrapping stamp tax on stock purchase and encouraging state-owned enterprises to buy back shares in their listed companies.

The state-owned investment company Central Huijin Investment Co announced on Tuesday that it had bought 2 million A shares from each of the country's top three state-owned banks.

Major shareholders from 42 listed companies have bought back their stakes, totaling 223 million, since August 28 when the securities regulator allowed big shareholders to raise their holdings by as much as 2 percentage points over 12 months.