* U.S. weekly jobless claims, Wal-Mart sales hurt dollar

* Dollar falls vs yen as risk aversion returns

* Stg bounces as BoE delivers 50 bps rate cut, as expected (Recasts, adds quotes, updates prices; changes byline, dateline, previous LONDON)

By Gertrude Chavez-Dreyfuss

NEW YORK, Jan 8 (Reuters) - The U.S. dollar tumbled against the yen on Thursday, as falling stocks worldwide and weak sales at U.S. retailer Wal-Mart tempered the market's appetite for risk and reignited worries about the global economic outlook.

The greenback also fell against the euro after the latest weekly data showed the number of Americans remaining on unemployment benefits rose to a 26-year high.

"That bit of optimism that lifted (the dollar) for the first few days faded after the FOMC minutes showed people just how concerned the Fed was about the U.S. economic outlook," said David Watt, senior currency strategist, at RBC Capital Markets in Toronto.

"And the ADP (ADP Employer Services) report (on U.S. private sector jobs) was a cold, hard slap of reality."

The dollar had rallied in the first few days of 2009, buoyed by the expectations for a U.S. stimulus package that many hope would help pull the economy out of recession. However, the optimism proved short-lived as fresh U.S. data, such as the steep drop in private sector jobs, showed that this could be a prolonged slowdown.