Brent and U.S. crude oil futures pared losses on Thursday, beset by deeper geopolitical concerns on witness reports that police fired upon protesters in Saudi Arabia's Eastern province.

The protest in the OPEC member's oil-producing Eastern province was the latest sign of growing unrest in the Arab world, which has sparked jitters about oil supply disruptions.

The news report that protesters were fired upon by police in Saudi Arabia has pulled crude up from the lows, said Phil Flynn, analyst at PFGBest Research in Chicago. Flynn referred to an initial report from the Associated Press.

In the Saudi protest, one witness told Reuters that police lobbed percussion bombs to disperse a crowd of about 200 people belonging to the kingdom's Shi'ite minority.

Earlier reports said activists have made unprecedented calls for mass protests against the kingdom's absolute monarchy on Friday.

Protests are also planned in other Gulf countries such as Yemen, Kuwait and Bahrain on Friday, after the day's religious prayers.

By 2:13 p.m. EST (1913 GMT), in London, April Brent crude was down 28 cents at $115.66 a barrel, trading from $113.52 to $116.55.

On the New York Mercantile Exchange, U.S. crude for April delivery traded down $1.24 at $103.14, after moving earlier between $100.62 to $105.06.

Earlier, oil prices had tumbled as the dollar strengthened on renewed Euro zone credit worries, but analysts said fears persisted that prolonged conflict in Libya could do long-lasting damage its oil infrastructure.

Oil prices were also pressured earlier by data showing that China, the world's second largest oil importer, unexpectedly posted the largest trade deficit in seven years, stirring global economic growth worries.

New U.S. jobless claims rose last week and the country's trade deficit widened in January, weighing further on U.S. crude.

(Additional reporting by Robert Gibbons in New York; Editing by Walter Bagley and Sofina Mirza-Reid)