Oil prices climbed Thursday as Libyan unrest offset a jump in US crude stockpiles, analysts said.
US benchmark West Texas Intermediate for delivery in April added 59 cents to $52.12 a barrel.
Brent North Sea crude for April also gained 59 cents to $61.14 a barrel approaching midday in London.
The US Department of Energy (DoE) on Wednesday said commercial crude inventories jumped by 10.3 million barrels in the week February 27, higher than analyst forecasts.
Inventories have set new records for five straight weeks, and US oil production is already high at 9.3 million barrels per day.
Libya's National Oil Corporation meanwhile declared force majeure Wednesday at 11 oil fields after attacks by Islamists, a legal step protecting it from liability if it cannot fullfil contracts for reasons beyond its control.
Libya has been awash with weapons since the 2011 uprising that toppled and killed dictator Moamer Kadhafi, and opposing militias have since been battling for control of its cities and oil wealth.
Fighting in the North African state, a member of the OPEC oil-producing cartel, has seen output reduced from a high of almost 1.5 million barrels per day to 150,000 a day, according to analysts.
"The political vacuum created in Libya by the different ethnic and armed groups has not only ensured the country’s oil production is very unlikely to rise anywhere near its 2012 high of 1.5 mbpd but it also provides the Islamic State with an open door to take advantage of the anarchy," oil brokers PVM wrote in a client note Thursday.
"A full-blown war between rival groups could reduce this level to naught which would significantly ease the current global oversupply," they added.