* Dollar index up 0.3 percent at 79.187
* Chinese shares fall 4.3 percent
* Sterling tumbles as some BoE members wanted bigger QE
(Adds quotes, data, updates prices)
By Tamawa Desai
LONDON, Aug 19 (Reuters) - The dollar and yen rose on Wednesday after Chinese shares extended losses, prompting investors to pull back from riskier assets.
The Shanghai Composite Index closed down 4.3 percent on Wednesday, led by recently listed shares as investors bailed out of the market, disappointed the authorities did not support the market which has fallen 20 percent in two weeks.
European shares were pulled lower, falling more than 1.0 percent by mid-morning trade, while U.S. S&P 500 futures index was also down nearly 1.0 percent.
Amid a dearth of major economic news, traders said the currency market was taking its cue from stock market moves.
"Chinese stocks were dumped into the close, and that provided an instant bid to the dollar, with everything coming off on the back of that," said Christian Lawrence, currency strategist at RBC Capital Markets.
The dollar index, which tracks the performance of the greenback versus a basket of six other major currencies, was up 0.3 percent at 79.187. A more positive outlook would emerge if the index were to break above 79.60, which is around the 55-day moving average, traders said.
The euro was down 0.2 percent at $1.4096.
The yen also rose broadly as investors fretted about recovery prospects for the global economy. By 0856 GMT, it was up 0.4 percent against the dollar at 94.31 yen while rising 0.6 percent against the euro to 133.07 yen.
"Confidence in the outlook may not be so readily found amongst investors as was so clearly the case in H1," said Neil Mellor, currency strategist at Bank of New York Mellon.
STERLING TUMBLES ON SURPRISE BOE SPLIT
Sterling extended losses after a surprise split vote in the Bank of England's decision earlier in the month showing governor Mervyn King and a few others calling for an even bigger 75-billion-pound increase to its quantitative easing programme.
Meeting minutes showed a split 6-3 vote, with Tim Besley and David Miles joining King's dissent. They were outvoted by a decision to expand the programme by 50 billion pounds.
Sterling fell 1.0 percent to $1.6386 while the pound dropped 1.4 percent against the yen to 154.59 yen.
The euro rose 0.8 percent to 86.04 pence.
Meanwhile, higher-yielding currencies such as the Australian and New Zealand dollars dipped, with the Aussie dollar easing 0.5 percent to $0.8214 and the kiwi also slipping 0.6 percent to $0.6698.
The Aussie had hit an 11-month high on Friday while the kiwi reached a 2009 peak, before both retreated as a sell-off in risky assets gathered pace since late last week. (Editing by Jon Boyle)