* S. Sudan govt says rebels seized capital of key oil-producing region
* Libya should use force to reopen oil ports - oil min
* Total refineries in France enter 11th day of strikes
(Updates throughout, recasts, changes dateline from previous Singapore)
LONDON, Dec 23 (Reuters) - Brent crude oil held steady above $111 a barrel on Monday amid slow activity ahead of the Christmas holiday as investors focused on ongoing refinery strikes in France and internal strife in South Sudan.
February Brent crude edged down 30 cents to $111.47 a barrel by 0953 GMT after gaining 2.7 percent last week. It touched a two-week high of $111.93 earlier in the session.
U.S. crude for February delivery was at $99.02 a barrel, down 30 cents.
Escalating tension and violence in South Sudan threatened the country's 245,000 barrels per day (bpd) oil output. The government said on Sunday rebels had seized the capital of a key oil-producing region.
This could add to the more than 1 million bpd of lost supply from Libya where key oil ports were shut by a group demanding greater autonomy for the country's eastern part.
South Sudan's ambassador in Khartoum said on Sunday that oil was flowing normally although the country's main investor China National Petroleum Company has evacuated its oil workers from the fields to the capital Juba.
"You've lost Libyan supply and you'll lose Sudanese supply. Although they are not large amounts, they are significant enough to make people nervous," said Jonathan Barratt, chief executive of commodity research firm Barratt's Bulletin in Sydney.
Libya's oil minister said on Saturday force should be used to reopen key oil ports in the eastern part of the country which have been closed for five months.
Workers at three of Totals' five French refineries entered an 11th day of strikes, piling further uncertainty to the oil demand and supply picture in the region.
"With the refinery strikes, France is currently boiling 600,000 bpd less crude. If the strikes continue then the other European refineries are likely to run a bit harder... but the U.S. will also contribute to replace the lost product output from the French refineries and net that should therefore result in lower crude oil demand in Europe," said Oliver Jakob, analyst at Zug, Switzerland-based Petromatrix.
Little economic data is scheduled to be published this week.
"The biggest input for the next two weeks is going to be lack of volume due to the holidays. Trading flat prices with conviction in such an environment will be a difficult task," Jakob said.
(Additional reporting by Florence Tan in SINGAPORE; Editing by Michael Urquhart and Muralikumar Anantharaman)