* FTSEurofirst 300 down 0.2 pct, Euro STOXX 50 down 0.3 pct
* Shift to Fed rate outlook sparks pullback in global stocks
* Impact on European stocks milder than on emerging markets
* Siemens boosted by UBS rating upgrade
PARIS, March 20 (Reuters) - European stocks fell in early trade on Thursday, mirroring a drop in global equities after U.S. Federal Reserve Chair Janet Yellen hinted at a potential earlier-than-anticipated increase in interest rates.
In comments which sent U.S. stocks and bonds sinking, Fed Chair Janet Yellen said the central bank will probably end its massive bond-buying programme in the fall, and could start raising interest rates around six months later.
"This is triggering a real correction in interest rates forecasts, with ripple effects hitting virtually all asset classes, from equities to forex," said David Thebault, head of quantitative sales trading, at Global Equities.
At 0837 GMT, the FTSEurofirst 300 index of top European shares was down 0.2 percent at 1,302.56 points, while the euro zone's blue-chip Euro STOXX 50 index was down 0.3 percent at 3,066.87 points.
However, the impact from the Fed's announcement on European stocks was milder than on emerging equities, with the MSCI emerging market index losing 1.3 percent.
The European stock market has been the big winner of sharp investment outflows from emerging countries, hurt in part by the scaling back of the Fed's quantitative easing programme, while investors increasingly bet on the euro zone economic recovery.
Around Europe on Thursday, Britain's FTSE 100 index was down 0.5 percent, Germany's DAX index down 0.5 percent, and France's CAC 40 down 0.4 percent.
"What makes investors nervous is that it sounds risky for the Fed to unveil a calendar when macro and micro signals are still quite mixed. Just look at FedEx's earnings," Global Equities's Thebault said.
FedEx Corp, the world's No. 2 package delivery company, on Wednesday posted lower-than-expected results and cut its fiscal-year profit forecast.
Bucking the trend, shares in Siemens gained 1.5 percent, the top gainers among European blue-chips, boosted by an upbeat note from UBS which lifted its recommendation on the stock to "buy" from "neutral", seeing upside potential following a weak performance so far in 2014.
"Since the start of the year the stock has underperformed the market and the sector by about 7 percent, and with several potential catalysts ahead, we think now is the time to buy back into the shares," UBS analysts say in a note.
Europe bourses in 2014: link.reuters.com/pad95v
Asset performance in 2014: link.reuters.com/rav46v
Today's European research round-up (Editing by Alison Williams)