* FTSEurofirst 300 down 0.5 pct
* Worries about U.S. rate hike make investors wary of M&A
* Orange, TDC fall after striking acquisitions
By Francesco Canepa
LONDON, Sept 16 (Reuters) - European equity indexes fell on Tuesday as nerves about a tightening in U.S. monetary policy sapped investor enthusiasm - even for new mergers & acquisitions activity.
France's Orange fell 1.2 percent after unveiling a deal to buy Spanish fixed line telecommunications operator Jazztel, whose shares surged 6 percent, adding to a 12 percent rise on Monday.
Shares in Danish telecoms group TDC were down 1.2 percent after it said it would buy Norway's second-largest cable operator, Get AS, in a bid to counter falling revenues in its home market by expanding in other markets.
At 0745 GMT, the FTSEurofirst 300 index of top European shares was down 0.5 percent at 1,375.46 points, falling further away from this month's 6-1/2 year high.
Investors were reluctant to dip back into the market ahead of the U.S. Federal Reserve's two-day policy meeting, due to start today, and a referendum on independence for Scotland from the United Kingdom on Thursday.
Justin Haque, a broker at Hobart Capital Markets, said the new M&A bout was a sign management teams were rushing to finalise deals in expectation of a rise in U.S. interest rates, which would increase borrowing costs and make financing acquisitions more expensive.
"Everybody is buying just before rates go up," said Haque. "The only clever people here are structural sellers."
British online fashion retailer ASOS tumbled 11.8 percent after downgrading its 2014-15 profit guidance. Sweden's Kinnevik, the largest shareholder in ASOS's competitor Zalando, fell 1.1 percent.
Europe bourses in 2014: link.reuters.com/pap87v
Asset performance in 2014: link.reuters.com/gap87v
Today's European research round-up (Editing by Catherine Evans)