Stock Connect is a cross-border investment scheme that allows offshore investors to buy onshore Chinese shares, and mainland investors to tap the Hong Kong market.

Hong Kong Exchanges and Clearing got into a rare public dispute with China's two mainland exchanges a year ago when the latter blocked Chinese smartphone maker Xiaomi Corp - at the time the only company listed in Hong Kong with dual-class shares - from the trading link. The Shanghai stock exchange said that mainland investors didn't understand the structure well enough.

Dual-class shares - which offer one type of shares for the general public and another type for a company's top executives and founders - give the company's management more of a say, which advocates say protect against pressure for short-term returns, but critics argue they could be abused by company insiders.

Meituan Dianping, a Chinese online food delivery-to-ticketing services firm, is the only other company listed in Hong Kong with such a structure, under Hong Kong's new rules designed to attract tech companies.

The Shanghai and Shenzhen stock exchanges said in statements on Friday that they were running a consultation on the agreed criteria for dual-class share trading until Aug. 9.

(Reporting by Noah Sin, Twinnie Siu, Julie Zhu and Alun John; Writing by Noah Sin; Editing by Susan Fenton)