* FTSEurofirst 300 down 0.1 percent, volumes weak
* Euro zone blue chip stocks at 16-month highs
* Momentum stalls on U.S. worries
* Media stocks rise, ITV buys U.S. stake
By David Brett
LONDON, Dec 24 (Reuters) - European shares closed provisionally lower in a thin last trading session before the Christmas break with investors opting to trim positions in the absence of a resolution to U.S. budget talks.
French, Dutch, Spanish and UK markets traded for only half the session while those in Germany, Italy, Austria, Greece, Denmark, Norway, Sweden and Switzerland were closed.
The FTSEurofirst 300 closed down 0.1 percent, at 1,138.14 points, still just a few points shy of an 19-month high of 1,144.15 hit last week.
"There are very few people in the office and most of the business being done is trimming positions after some decent year-end gains," a London-based trader said.
The euro zone's blue chip Euro STOXX 50 index and France's CAC 40, which are trading around 16-month highs, closed down 0.1 percent and 0.2 percent respectively. Spain's IBEX finished up 0.1 percent and Britain's FTSE 100 index was up 0.2 percent; they are both at around 9-month highs.
Rebecca O'Keeffe, head of investment at Interactive Investor, said the march higher was largely the result of investors betting U.S. policymakers will avoid the so-called fiscal cliff and that Europe's debt crisis is abating.
After shunning European assets most of the year because of fears the crisis would lead to a break-up of the euro zone, investors have shown appetite for European stocks recently, according to EPFR Global data.
But momentum has been stalled by concerns over the talks between U.S. Democrats and Republicans to avoid around $600 billion in automatic tax hikes and spending cuts that could drag the world's biggest economy back into recession.
"Events last week highlight the yawning gap that still remains between the Republicans and Democrats and suggest that investor optimism may be misplaced," Interactive Investor O'Keeffe said.
The majority of sectors ended in negative territory, but media shares managed a 0.3 percent rise boosted by M&A activity at London-listed broadcaster ITV.
ITV rose 0.6 percent after announcing the purchase of a 61.5 percent stake in U.S.-based Gurney Productions, which makes reality programmes.