* FTSEurofirst 300 up 0.1 pct after hitting 7 1/2-year peak
* DAX underperforms, led by Siemens, K+S
* FTSE 100 hits record high; 7,000 mark in sight
By Francesco Canepa and Blaise Robinson
LONDON\PARIS, March 19 (Reuters) - European stocks paused after hitting a 7-1/2-year high on Thursday, capped by falls in Germany's Siemens DE> and K&S due to concerns about the impact of lower commodity prices on their profits.
Shares in industrial group Siemens slid 5 percent after the group Chief Executive Joe Kaeser said on Thursday he was worried that the slump in oil prices is discouraging oil-exporting countries from investing in infrastructure.
Chemical firm K&S dropped 3.1 percent in heavy volume on reports of lower potash prices in deals struck by exporter Belarus.
The stocks led fallers on Germany's Dax, which was down 0.6 percent at 1507 GMT, succumbing to some profit-taking after a 20 percent rally since the start of the year.
The FTSEurofirst 300 index of top European shares was up 0.1 percent at 1,592.25 points, after climbing to a 7 1/2-year high earlier in the session.
Euro zone markets have been boosted by the European Central Bank's bond-buying programme, known as quantitative easing, which has depressed returns on bonds and knocked down the euro.
This has fuelled bets that a weaker euro would stimuate the region's economy and corporate earnings.
"We are in a very overbought situation in the European market because everyone has poured money into it," Michael Testorf, co-portfolio manager of the RSQ International Equity Fund.
"(But) when the whole of QE filters though to the final consumer...you will see earnings surprises and a further economic upswing."
Britain's FTSE 100, also up 0.1 percent, had touched a record high in early deals as markets cheered an accomodative message from the Fed.
The Fed removed the word "patient" from its statement in terms of raising interest rates, as expected, but also lowered its forecasts for the economy and inflation and for its interest rate trajectory. That signalled a more gradual path to policy normalisation than many investors had foreseen.
Shares in Enel rose 1.9 percent after the Italian utility said it aims to raise profits and dividends over the next five years by focusing on emerging markets and green energy, after writedowns caused its 2014 net profit to fall 84 percent.
British clothing retailer Next, down 3.8 percent, featured among the top losers in Europe after the company gave a cautious outlook for the 2015-16 year.
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up (Additional reporting by Alexandre Boksenbaum-Granier; Editing by Mark Heinrich)