European shares retreated from a one-month high on Thursday, with uncertainty regarding the European Central Bank's possible move to ease policy to stimulate growth prompting investors to trade cautiously.
Investors awaited a slew of data releases on both Thursday and Friday for hints about the market's direction in the near term. Speculation of a quantitative easing (QE) programme has grown since ECB President Mario Draghi struck a dovish tone at the Jackson Hole meeting last week.
But ECB sources said late on Wednesday the central bank was unlikely to take new policy action next week unless August inflation figures on Friday show the euro zone sinking significantly towards deflation.
"The market's primary focus appears to be on the ECB and the likelihood and exact timing of any possible QE policy action," said Robert Parkes, director of equity strategy at HSBC.
"There has been some caution as investors are getting mixed signals. Further economic indicators could provide some hints about the ECB's next move."
Investors were also awaiting preliminary German inflation data due later in the session for hints about how soft the euro zone numbers might turn out. Other data releases include euro zone economic sentiment indicators.
At 0820 GMT, the pan-European FTSEurofirst 300 index was down 0.5% at 1,370.47 points after hitting a one-month peak in the previous session.
Miners were the worst hit, with the STOXX Europe 600 basic resources index falling 1.6 %, led lower by a 3% drop in shares of global miner Rio Tinto as the sector was hit by a drop in iron ore prices in China, the world's biggest metals consumer.
Among individual sharp movers, Bureau Veritas fell 6 % after Barclays and Jefferies cut their target prices for the company's stock, despite it posting a 1.8 % rise in first-half revenue on an organic basis.
On the positive side, Essilor climbed 4.9% after the world's largest maker of opthalmic lenses forecast full-year revenue growth of more than 13 % excluding currency effects following a 7.9 % rise in first-half sales.