* Strife in S. Sudan, Libya, strikes in France cap losses
* NYMEX trading closes an hour early on Tuesday, Dec. 24
* Oil inventories seen declining for 4th week - poll
* Coming up: API inventory report, Tuesday 4:30 p.m. EST
(Adds new quote, oil inventory poll, updates to settlement prices)
NEW YORK, Dec 23 (Reuters) - Crude oil futures slipped on Monday in light volume as traders booked profits after three days of gains ahead of the Christmas holiday, though refinery strikes in France and internal strife in producers Libya and South Sudan checked losses.
U.S. gasoline futures ended near flat, after reaching a fresh 15-week high earlier in the session as refinery outages in the United States and Europe continued to boost demand for the fuel.
"RBOB (gasoline) has had a nice run up here and I think there has been stronger underlying demand, strong export demand, some refinery issues here in the Northeast and turnaround starting soon," said Andy LeBow, vice president at Jefferies Bache in New York.
Brent crude ended 21 cents lower at $111.56 per barrel, after touching a two-week high of $111.93.
U.S. crude oil futures for February delivery fell 41 cents to $98.91 a barrel, off a two-month high of $99.40 reached in the previous session.
The spread between the two benchmarks <CL-LC01=R> widened slightly to end at $12.65 per barrel.
U.S. RBOB gasoline futures settled 0.1 percent lower at $2.7803 per gallon, after trading as high as $2.7933, the highest level since Sept. 10.
The crack, or difference, between U.S. crude oil futures and gasoline <CL-RB1=R> widened to a three-week high of $18.35 per barrel amid tight supply during the holiday driving season.
Rising tensions in Africa and the Middle East capped losses in Brent as the market viewed the unrest as a risk to supply.
Escalating violence in South Sudan threatened the country's 245,000 barrels per day (bpd) oil output.
South Sudan's government remains in control of the country's oil fields, the information minister said on Monday, although the country's main investor China National Petroleum Company has evacuated its oil workers from the fields to the capital Juba.
This could add to the more than 1 million bpd of lost supply from Libya where ports were shut by a group demanding greater autonomy, analysts said.
Libya's oil minister said on Saturday force should be used to reopen oil ports in the eastern part of the country which have been closed for five months.
The market also awaited oil inventory data on Tuesday and Friday to gauge supply. U.S. crude oil inventories likely fell for the fourth straight week last while gasoline inventories rose, a preliminary Reuters poll of analysts showed on Monday.
The American Petroleum Institute's weekly petroleum stocks report will be released as usual on Tuesday, Dec. 24, at 4:30 p.m. EST (2130 GMT).
The U.S. Energy Information Administration's (EIA) weekly report of crude oil, distillate and gasoline stocks will be released on Friday, Dec. 27, at 11 a.m. EST (1600 GMT), two days later due to the Christmas holiday on Wednesday.
Trading in U.S. oil futures, ultra low-sulfur diesel and gasoline futures on the New York Mercantile Exchange will close one hour early on Christmas Eve, Dec. 24, at 1:30 p.m. EST (1830 GMT). Trading is shut on Dec. 25, Christmas Day.
(Additional reporting by Jeanine Prezioso in New York, Ron Bousso in London, Florence Tan in Singapore; Editing by William Hardy, Leslie Gevirtz, David Gregorio, Andrew Hay and Marguerita Choy)