GLOBAL MARKETS-Shares steady after rally, dollar jumps
* World shares stable at 18-month highs
* Concerns over U.S. battles to cut spending, raise debt ceiling
* Dollar index hits three-week high, euro falls
* Brent oil falls with other commodities as dollar gains
NEW YORK, Jan 3 (Reuters) - World stocks stalled on Thursday as traders were cautious after equities hit an 18-month high, while the U.S. dollar climbed to a three-week high against a basket of currencies on concerns about more budget wrangling in Washington.
Data suggesting some momentum in the U.S. economy as the year ended showed private-sector employers stepped up hiring in December, allowing for the upward tick in stocks and further supporting the greenback.
President Barack Obama and congressional Republicans face two more months of tough talks on spending cuts and an increase in the nation's debt limit as the hard-fought deal to avert the "fiscal cliff" of automatic tax hikes and spending cuts covered only taxes and delayed decisions on expenditures until March 1.
"There's still some clouds over the horizon, with the fiscal issue of the government," said Jeff Meyerson, head of trading at Sunrise Securities in New York. "We don't know how they're going to pan out, but in all likelihood there's not going to be a calamity."
The MSCI world equity index advanced less than 0.1 percent, reversing a dip through most of the session after hitting an 18-month high on Wednesday.
A European equity benchmark ended up 0.45 percent after hitting its highest intraday level since March 2011, boosted by a belated reaction in Swiss stocks due to a holiday.
The Dow Jones industrial average was up 7.03 points, or 0.05 percent, at 13,419.58. The Standard & Poor's 500 Index was up 1.57 points, or 0.11 percent, at 1,463.99. The Nasdaq Composite Index was up 2.49 points, or 0.08 percent, at 3,114.75.
The euro tumbled against the dollar as investors grew worried about more budget fights ahead. Analysts say the market could be set up for volatility as Obama and congressional Republicans tussle over the next two months.
The dollar was up 0.4 percent against a basket of major currencies at a three-week high of 80.13, although it slipped 0.4 percent against the yen to 86.97.
"We really just kicked the can down the line and we're set up for another fight on the hill in the next month and a half or so," said John Doyle, currency strategist at Tempus Consulting in Washington.
The euro, which had touched an 8-1/2 month high against the dollar on Wednesday, was down 0.6 percent at $1.3110.
Investors will now turn their attention to Friday's December U.S. employment report. It is expected to show modest job growth of around 150,000, compared with 146,000 in November.
The ADP National Employment Report showed Thursday the U.S. private sector added 215,000 jobs in December, comfortably above economists' expectation of a 133,000 gain. Following the recent rally in equities, any disappointment in Friday's payrolls number could trigger a profit-taking sell-off.
DOLLAR JUMP HITS COMMODITIES
The dollar's strength and rising oil supplies pushed crude prices lower, with Brent down 0.1 percent to $112.31 a barrel. U.S crude futures were down 0.1 percent at $93.15.
Analysts expect oil prices to drop in 2013 as supply outweighs demand, especially after U.S. crude production hit a 19-year high in 2012.
Gold futures followed commodities lower and were down about 0.6 percent at $1,676.41 an ounce.
Thursday's retreat across riskier asset markets might have been sharper but for data showing activity in China's services sector and at U.S. factories expanded in December, brightening the outlook for global growth.
China's official purchasing managers' index for the non-manufacturing sector rose to a four-month high in December, adding to signs of a revival in the world's second-largest economy.
U.S. Treasury debt prices eased, pushing yields to three-month highs after the U.S. private jobs data cut into the appeal of safe U.S. government issues. Treasuries had already sold off sharply on Wednesday following the U.S. government deal to avoid the so-called "fiscal cliff."
The benchmark 10-year U.S. Treasury note was down 7/32, the yield at 1.8618 percent, a 15-week high.