* FTSEurofirst 300, Euro STOXX 50 flat
* FTSEurofirst +13.8 pct in 2012, ESTOXX +14.5 pct
* Euronext markets close at 1300 GMT, UK market 1230 GMT
* German, Swiss, Italian, Greek, Nordic markets closed
PARIS, Dec 24 (Reuters) - European shares were broadly steady on Monday, consolidating sharp gains made in the past five weeks, with volumes set to be thin for the traditionally quiet half session ahead of the Christmas break.
A number of European markets such as the French, Dutch, Spanish and UK ones will only trade for half the session on Monday, while trading in Germany, Italy, Austria, Greece, Denmark, Norway, Sweden and Switzerland is closed.
At 0900 GMT, the FTSEurofirst 300 index of top European shares was down 0.02 percent, at 1,138.91 points, still just a few points shy of an 19-month high of 1,144.15 hit last week.
The euro zone's blue chip Euro STOXX 50 index was flat, Britain's FTSE 100 index was up 0.17 percent, France's CAC 40 down 0.04 percent and Spain's IBEX up 0.14 percent.
Investors remained cautious as talks between U.S. Democrats and Republicans to avoid the so-called fiscal cliff - automatic tax hikes and spending cuts that could drag the world's biggest economy back into recession - were stalled on Monday, with President Barack Obama and House Speaker John Boehner out of Washington for the Christmas holidays.
"The gap between the positions of Democrats and Republicans has been tightening, but the outcome remains uncertain," Edmond de Rothschild Asset Management strategists wrote in a note.
"But the macro data remains quite positive. We're still 'overweight' equities, and we buy the dips to further increase our exposure to the asset class. The risk premium linked to the euro zone debt crisis should drop further next year."
The FTSEurofirst 300 is up 13.7 percent in 2012 while the Euro STOXX 50 has gained 14.5 percent. Both indexes are set to post their best annual performances since the sharp bounce of 2009, boosted by bold measures from central banks to revive global growth and resolve the euro zone debt crisis.
"This year has been a year of transition, and now it's time to turn the page and move on, to start picking stocks again for the long term, companies exposed to the emerging consumer in places like Asia and Africa," said David Thebault, head of quantitative sales trading, at Global Equities.
After shunning European assets most of the year because of fears the region's debt crisis would lead to a break-up of the currency bloc, investors have shown appetite for European stocks recently, according to EPFR Global data.
Europe equity funds enjoyed inflows last week, with US-domiciled funds extending their current inflow streak to 19 straight weeks, the data showed.
Euronext markets will be closing at 1300 GMT, while UK markets will close at 1230 GMT.