* Dollar held back by Bernanke comments on Fed policy
* Japan trade data shows higher-than-forecast deficit
* Euro falls back after hitting 4-year high vs yen
By Laurence Fletcher
LONDON, Nov 20 (Reuters) - The dollar edged lower on Wednesday after U.S. Fed Chairman Ben Bernanke said the Fed will maintain its ultra-easy monetary policy for as long as needed.
The dollar fell 0.2 percent against the yen at 99.95, having risen for much of the past month on expectations the United States will begin to wind down its stimulus.
In a speech that echoed dovish comments by his nominated successor, Janet Yellen, Bernanke said that while the economy had made significant progress, it was still far from where officials wanted it to be.
Bernanke said officials wanted evidence of durable job growth before scaling back the Fed's bond-buying stimulus, adding that interest rates were likely to remain near zero for a considerable time after the asset purchases end.
Investors will focus later on the minutes of the Federal Open Market Committee's October meeting, looking for clues to how soon policymakers may be prepared to scale back monetary easing.
The FOMC next meets on Dec. 17 and 18.
"There might be a few jitters going into the December FOMC, whether they start to taper or ... cut the (unemployment) threshold," said Paul Robson, currency strategist at RBS. "That might keep the dollar on the back foot."
The dollar index was marginally lower at 80.679, having earlier fallen to 80.535. The euro edged down to $1.3534.
The euro was down 0.2 percent against the yen at 135.31 yen. It hit a four-year high of 135.42 yen in early Asian trade.
Data showed Japan logged a trade deficit of 1.09 trillion yen ($11 billion) in October, a record for the month and above a median forecast of 813.5 billion yen, even as exports rose by their largest amount annually in three years.
"The trade data was a little bit soft," said RBS's Robson. "That suggests Japanese authorities will have to do more on the currency."
Analysts said the low-yielding yen was still the preferred funding currency for carry trades, with the Bank of Japan expected to maintain its ultra-loose monetary policy when it meets on Thursday.
The Australian and New Zealand dollars gave back some recent gains. The Aussie fell 0.5 percent to $0.9385 after Reserve Bank of Australia Assistant Governor Guy Debelle said a fall in the Aussie would be preferable.
The kiwi was also down by 0.5 percent at $0.8325.
The U.S. dollar had already been unsettled after China signalled on Tuesday it was willing to tolerate a stronger yuan, meaning it was less likely to buy U.S. dollars to keep its currency pinned down.
"Although no timeline was provided, the news should be supportive of further yuan appreciation," analysts at Barclays Capital wrote in a note to clients.