Crude oil prices fell more than $2 a barrel on both sides of the Atlantic on Thursday, sunk by weak economic data hinting at softening oil demand and by ample supplies.
The U.S. crude contract retreated more than 50 cents in a minute as shares of the exchange-traded U.S. Oil Fund saw high-volume trading.
U.S. crude fell about 60 cents to a then session low of $96.03 between 10:50 and 10:51 a.m. EDT (1450 GMT).
At 10:51 a.m., almost 1 million USO shares traded in just one minute, more than a third of the average 60-day daily volume.
"The market had never been below $96.55 for the whole month of August. That was the final straw," said Rich Ilczyszyn, chief market strategist and founder of iitrader.com LLC in Chicago.
"Once we broke that low, people that are long the market exit the strategy. New sellers come in and get the ball rolling to the downside."
The United States Oil Fund LP is an exchange-traded security that tracks the daily prices of West Texas Intermediate light sweet crude oil, the company's website says.
U.S. crude quickly bounced off that low, before resuming the retreat. The contract settled down $2.01 at $95.58 a barrel.
Brent and U.S. crude futures were already pressured by weak European economic data and ample global oil supply, despite conflicts in Iraq and Libya.
Brent crude for delivery in September settled down $2.27 at $102.01 after dropping to a low of $101.92 , the lowest since July 2013.
The October Brent contract lost $2.99 to settle at $102.07.
The deficit of the September Brent contract to the October contract, at 78 cents based on Wednesday settlements, narrowed to settle at 6 cents on Thursday, its smallest discount at settlement since July 7.
Germany's economy shrank in the second quarter and France posted no growth, data showed on Thursday, adding to jitters after the European Union and Russia imposed sanctions on each other over Ukraine.
"The market continues to grind lower in search of a bottom. There are growing fears about economic growth, in particular in Europe and China, and I think you're getting greater expectations that more Libyan oil is going to hit the market," said Gene McGillian, analyst at Tradition Energy in Stamford, Connecticut.
The European news followed data on Wednesday from China that included a 6 percent fall in July implied oil demand from June, adding to concerns.
LACK OF DISRUPTIONS
A tanker carrying crude left Ras Lanuf in Libya on Tuesday and a National Oil Corp official said on Thursday Libya would resume exports from Es Sider in "a few days".
In OPEC's second-largest producer, advances by Islamic State militants in the north of Iraq have so far had little impact on output from its southern oilfields.
"The supply outlook has been pretty rosy. OPEC production has been pretty good. Supply in Iraq is unaffected," said Phin Ziebell, economist at the National Australia Bank.
OPEC output rose to a five-month high above 30 million barrels per day in July and U.S. crude production averaged an estimated 8.5 million bpd, according to reports on Tuesday from the International Energy Agency and the EIA.
(By Anna Louie Sussman and Robert Gibbons; Additional reporting by Robert Gibbons and Josephine Mason in New York and David Sheppard and Jason Neely in London; Editing by Marguerita Choy, Bernadette Baum, Andre Grenon and James Dalgleish)