* HSI: -4.7 pct; CSI300: -1.0 pct; SSEC: -1.2 pct;
* Hong Kong tumble led by financials, HSBC slumps
* Brexit impact on China less than on Hong Kong
SHANGHAI, June 24 (Reuters) - Hong Kong stocks tumbled nearly 5 percent on Friday morning, joining global market turmoil as partial returns showed Britain was voting to leave the European Union.
China shares, which are less vulnerable to world market volatility, fell over 1 percent, although some traders warn the market has not fully priced-in the impact of a Brexit.
Hong Kong's Hang Seng index tumbled 4.7 percent, to 19,894.12 points, the lowest level in a month. The Hong Kong China Enterprises Index dropped 4.6 percent, to 8,382.86.
In China, the blue-chip CSI300 index fell 1.0 percent while the Shanghai Composite Index lost 1.2 percent.
As Brexit appeared increasingly likely, Charles Wang, chairman of Appleridge Capital Management Co., said it "is not necessarily a bad thing for Britain in the long term ... but in the short term, its impact on global markets could be even bigger than the European debt crisis."
Wang, who invests in both Hong Kong and mainland stocks, said he has over the past few days liquidated all his equity positions, and has been increasing investment in gold.
"Risks from such political events are too huge, and I don't bet on something which is out of my control. Over the next few weeks, you'll see a lot of volatility, and gold is the safe haven," he said.
Shares fell across the board in Hong Kong, led by financial and energy stocks.
An index tracking Hong Kong-listed financial stocks tumbled 6 percent, with British lender HSBC Holdings slumping 10.9 percent, in heavy trading, to its lowest level in nearly three months.
In China, all main sectors fell, with financials and energy shares leading the decline.
"Hong Kong is highly vulnerable to global sentiment ... the mainland market is less sensitive," said Appleridge's Wang. "But today, it has not yet priced in the impact of a possible Brexit."
ANZ said in a research note that although the Brexit result is unlikely to affect China's immediate economic outlook, the event "reminds us that we are still pencilling in one more additional RRR cut."
Reporting by Samuel Shen and Nathaniel Taplin; Editing by Richard Borsuk