A bold move to quadruple the daily quota of the two stock connects between the Chinese mainland and Hong Kong could essentially set the stage for a historic opening of the mainland's financial sector, but a higher level of regulation is required, said experts.

"The move, poised to increase integration of the mainland's onshore and offshore stock market trading, could make a big difference for years to come, if not immediately," said Fielding Chen Shiyuan, a Hong Kong-based Asia economist at Bloomberg Intelligence.

The daily northbound quotas for each of the Shanghai and Shenzhen stock connect schemes will be expanded fourfold to 52 billion yuan ($8.27 billion) from 13 billion yuan starting from May 1, People's Bank of China Governor Yi Gang told a panel discussion at the Boao Forum for Asia on Wednesday.

The daily quota for southbound trading, which allows investors in the Chinese mainland to buy Hong Kong stocks, will be boosted to 42 billion yuan from 10.5 billion yuan.

Currently, the daily trading quotas under the two stock connects account for 20 percent of Hong Kong stock turnover and 5 percent of the trading volume in the Chinese mainland stock markets, Chen noted.

The fourfold expansion would send the proportions to 80 percent and 20 percent, respectively, making the Hong Kong stock market almost totally open to mainland investors, and opening the door of the mainland equity market much wider to overseas investors, Chen reckoned.

Echoing remarks from Norman Chan Tak-lam, chief executive of the Hong Kong Monetary Authority, who said the expansion would help ensure the imminent inclusion of domestic A-shares in the MSCI Emerging Markets index proceeded smoothly, Sally Wong, chief executive of the Hong Kong Investment Funds Association, said the move comes as a "much-needed booster" for overseas investors, who have long been held at arm's length from the financial sector in the Chinese mainland.

"What matters is not a large increase in sheer numerical terms. Instead, the move sent a clear message that Chinese mainland policymakers attach great significance to overseas institutional investors," Wong said.

On Wednesday, Yi also vowed to speed up work on a stock trading tie-up between Shanghai and London, and is looking to get the mega project off the ground within the year.

Chen said the stock trading scheme, the third of its kind giving foreign investors access to mainland equity markets, would win the mainland bourse a worldwide reputation.