Oil prices fell on Thursday after weak U.S. economic data spurred worries over crude oil demand.
U.S. crude declined $2.23, or 4.6 percent, to settle at $46.25 a barrel. was last down $1 to trade around $48 a barrel.
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 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.
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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."
The Labor Department also released a report showing claims for state unemployment benefits rose last week. Total claims climbed to 316,000, past the 300,000 threshold that is associated with a firming labor market.
Hastings called the jump a "significant uptick."
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"That uptick in jobless claims is something that will really get the entire market reacting," he said.
Bank of America Merrill Lynch cut its crude oil price forecasts on Thursday, saying Brent could go as low as $31 by the end of the first quarter of 2015.
"Stocks all over the world are building at a very fast rate," analysts at the bank said in a note to clients, saying very high inventories would make any sharp recovery in prices much less likely.
Both crude oil benchmarks hit their lowest levels for almost six years earlier this week on a global oversupply of high quality oil.
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This provided some support for crude, contrasting dominantly bearish news.
In its monthly report, the Organization of the Petroleum Exporting Countries forecast demand for the group's oil would drop to 28.78 million barrels per day in 2015, down 140,000 bpd from its previous expectation.