Oil prices fell on Thursday after weak U.S. economic data spurred worries over crude oil demand.
Early in the session, U.S. crude moved higher, breaking above $50 a barrel on a fall in the dollar. U.S. crude also briefly traded at a premium to Brent, rather than the discount it normally sustains, as the Brent front-month contract traded in its last day before expiry.
The front-month Brent futures contract was due to expire later on Thursday, and traders said investors who had sold at higher levels in recent days and weeks were buying back futures to take profit after recent heavy price falls.
The Philadelphia Federal Reserve Bank released a survey saying factory activity in the U.S. mid-Atlantic region grew at a slower pace this month. The bank's business activity index fell to its lowest in almost a year.
The slowing activity is another bearish macroeconomic fundamental for the market, said Richard Hastings of Global Hunter Securities.
"The expectation is that aggregate demand is not going to be that robust" a year from now, Hastings said. "And that is enough to generate the selling activity that's dominating the mood of the markets."