* Pan-European index down more than 1 percent
* Miners top decliners as metals slip
* Galenica shares slump after results (Adds detail, updates prices)
By Atul Prakash and Danilo Masoni
LONDON/MILAN, March 15 (Reuters) - European shares retreated on Tuesday, led lower by commodity stocks, after the Bank of Japan left policy unchanged but presented a bleaker view of the country's economy.
Weak U.S. retail sales data also raised concern about growth prospects for the world's largest economy, just before the Federal Reserve's policy statement on Wednesday, which will be closely monitored for clues to future interest rate moves.
"The market is wary of potentially hawkish remarks that would suggest a June rate rise is firmly back on the table," said Gain Capital Fawad Razaqzada. "But in the event that the Fed sounds more dovish than expected, stocks are likely to stage a relief rally."
Earlier on Tuesday, the Bank of Japan said it would maintain its asset-buying programme at existing levels but offered a bleaker view of the economy, suggesting it may roll out more stimulus to reach an elusive inflation target.
The STOXX Europe 600 Basic Resources index fell 5.2 percent, the top sectoral decliner, as copper prices dropped. The European oil and gas index was also down 1.9 percent as crude oil prices slipped.
Shares in BHP Billiton, Glencore, Rio Tinto and Antofagasta fell 4.2 to 6.7 percent, putting pressure on the pan-European FTSEurofirst 300 index , which was down 1.1 percent at 1,341.5 points by 1512 GMT.
Galenica shares slumped 13 percent after the healthcare company announced its results and confirmed the group planned to divide itself into two independent listed companies in the fourth quarter of this year.
Traders said its shares fell as the company's outlook was vague and disappointing.
Bucking the trend, French telecoms operator SFR rose 1.6 percent. The company reported its core operating profit rose 20 percent to 3.86 billion euros in 2015 as cost cuts offset declining mobile subscribers.
Today's European research round-up (Editing by Larry King)