European shares fell on Wednesday, erasing gains made at the start of trading, as the Bank of England reignited worries that equity markets may get less support from major central banks in future.
Injections of liquidity by the U.S. Federal Reserve, whose head Ben Bernanke is due to speak later on Wednesday, and other major central banks have hit returns on bonds and led investors to the better returns available from equities.
However, that global equity rally has stuttered over the last two months on expectations the Fed will eventually scale back such measures on growing signs of an economic recovery, and the Bank of England sent a similar message on Wednesday.
Minutes from the last Bank of England meeting - the first chaired by new governor Mark Carney - showed that all its policymakers voted against extending the bank's bond-buying programme, known as "quantitative easing" (QE).
The pan-European FTSEurofirst 300 index was down by 0.4 percent at 1,186.26 points in mid-session trading, while the euro zone's blue-chip Euro STOXX 50 index fell 0.6 percent to 2,649.55 points.
The pan-European STOXX 600 index was also down by 0.4 percent at 294.01 points.
Mike Turner, European equity options broker at XBZ Ltd, said investors were buying up "put" options - used to bet on a market fall - as caution had crept in again due to uncertainty over future central bank monetary policy from the Fed and others.
"Renewed portfolio protection has gone into place. The appetite for risk-on trades has diminished," he said.
Turner said that, among other contracts taken out, investors had "put" options due to expire on Friday on the Euro STOXX 50 with a strike price of 2,550 points - implying a possible 100 point fall on that index by the end of this week.
Citigroup equity strategists also expected European equity markets to be pinned back ahead of the Friday options expiry.
It expected the Euro STOXX 50 to be pinned to around the 2,700 point level, and for Germany's DAX, which was down 0.6 percent at 8,152.31 points, to be stuck around the 8,200 point level.
The FTSEurofirst 300, which has risen some 5 percent since the start of 2013, hit a five-year high in late May of 1,258.09 points but then dropped to a 2013 low of 1,111.11 points in late June on expectations the U.S. Federal Reserve would scale back stimulus measures.
It has since rallied, helped by some upbeat corporate earnings with Swiss drugmaker Novartis and technology group ASML raising their full-year outlooks on Wednesday.
However, some 415 billion euros ($545.21 billion) have been wiped off the market capitalisation of companies in the STOXX 600 index since Bernanke raised the possibility in May that the Fed would scale back its stimulus measures. ($1 = 0.7612 euros)