Oil prices rose Thursday on concerns about output in conflict-wracked South Sudan and the latest round of improving US economic data. US benchmark West Texas Intermediate for February delivery rose 33 cents to $99.55 a barrel on the New York Mercantile Exchange. European benchmark Brent oil for February delivery increased 8 cents to $111.98 a barrel on the Intercontinental Exchange in London. Volume on electronic exchanges was low due to the Boxing Day holiday, which closed major markets in London. Traders have been keeping an eye on developments in South Sudan, which has been rocked by a wave of deadly ethnic violence. Analysts say the conflict threatens oil output in South Sudan, where some oilfield staff has been evacuated. Robert Yawger, director of energy futures at Mizuho Securities, said South Sudan usually exports about 220,000 barrels a day to Japan, Malaysia and China. The UN Security Council said Thursday it was hurrying to deploy reinforcements to its peacekeeping force in the country, as neighboring states Kenya and Ethiopia try to broker a solution to the crisis. Oil also gained after a Department of Labor report showed first-time claims for unemployment benefits fell to 338,000, below the 350,000 forecast by analysts. The better jobless claims report came on the heels of other recent strong US data on third-quarter growth, durable goods orders and other items that suggest a healthier economy. "The improving US economy and signs the global economy is steady has been driving prices higher," said Gene McGillian, broker and analyst at Tradition Energy. Markets are eyeing the weekly report on US oil inventories, which is delayed until Friday due to the Christmas holidays. Analysts expect a decline in stocks of 2.2 million barrels, according to a survey by the Wall Street Journal.