Oil prices Wednesday sank on fresh signs of economic weakness in the United States and China and after a US inventory report showed crude stocks at their highest point in more than 30 years.
US benchmark West Texas Intermediate for June delivery settled at $91.03 a barrel, down $2.43 or about 2.6 percent.
European benchmark Brent futures lost $2.42 to close at $99.95 a barrel.
The decline came after a stream of disappointing economic data from the US and China, the world's top two oil-consuming countries.
The US private sector added just 119,000 jobs in April, the lowest level in seven months, according to payrolls firm ADP.
US manufacturing activity also slowed in April, according to a report by the Institute for Supply Management. The ISM manufacturing purchasing managers index (PMI) fell to 50.7 in April from 51.3 in March, not much above the 50-point line that separates growth and contraction.
Earlier in the day, China reported a fall in manufacturing activity, with the Chinese PMI dipping to 50.6 in April from 50.9 in March.
"Overall it doesn't really suggest an environment of rapid demand growth," said Kyle Cooper, managing partner at IAF Advisors in Houston, Texas.
On the supply side, Wednesday's weekly US oil inventory report showed US supplies at their highest level since the government began collecting the data in 1982.
Crude oil stocks soared 6.7 million barrels, well above the 800,000 barrels forecast by analysts, according to a survey by Dow Jones Newswires.
Such historically high stocks are a sign of the US production boom with the rise of shale oil.
"It's just indicative of these shale plays ramping up," said Matt Smith, an analyst at Schneider Electric, an energy management firm. "It tells us we're in the middle of an oil boom."
Oil prices rallied slightly in the afternoon following news that the Federal Reserve would maintain its aggressive stimulus measures. But the Fed action, which was expected, was not nearly enough to take oil into positive territory.