* CSI300 +0.5 pct; SSEC +0.5 pct; HSI: 0.4 pct;
* Market aided by fading Brexit fears, Fed's cautious tone on rate
* ChiNext shares firm on Shenzhen-Hong Kong Connect hopes
SHANGHAI, June 22 (Reuters) - China and Hong Kong shares rose on Wednesday morning, as more investors bet Britain will vote to stay in the European Union this week, while Federal Reserve Chair Janet Yellen's cautious tone on future rate hikes also soothe market sentiment.
China's blue-chip CSI300 index and the Shanghai Composite Index both climbed 0.5 percent, to 3,121.66 points and 2,891.39 points, respectively.
In Hong Kong, both the Hang Seng index and the Hong Kong China Enterprises Index added 0.4 percent.
Risk appetite in global markets was helped by opinion polls in recent days that showed rising momentum for the "Remain" camp ahead of Thursday's British referendum on its EU membership.
"The chance of Brexit is getting smaller," said Yang Hai, strategist at Kaiyuan Securities.
"Even if it happens, I'm sure central banks around the world would act to stem a possible market chaos, and the impact on China could be limited."
Meanwhile, Yang shrugged off news that China's central bank will allow qualified foreign firms to issue stocks on the mainland, saying such a plan could take a long time, as many domestic companies are still waiting in a long queue for a listing.
But Shenzhen's start-up board ChiNext outperformed, after the People's Bank of China said on Tuesday that a stock connection between Shenzhen and Hong Kong will come "at an appropriate time".
The remarks rekindle hopes that the cross-border scheme will be announced on July 1, which is the anniversary of the handover of Hong Kong from the United Kingdom to mainland China in 1997.
Most sectors in both China and Hong Kong rose.
Chinese home appliance maker Midea, which is bidding for control of German industrial robot maker Kuka , rose slightly, after news that Kuka's supervisory board has given CEO Till Reuter a free hand for the takeover negotiations.
Hong Kong's index heavyweight Tencent Holdings Ltd jumped 2.1 percent, after China's biggest gaming group said it would buy a majority stake in 'Clash of Clans' mobile game maker Supercell to expand its interest overseas.
Reporting by Samuel Shen and Nathaniel Taplin; Editing by Simon Cameron-Moore