Oil prices fell more than 2 percent on Wednesday, with Brent futures dipping below $100 a barrel as fresh concerns over economic growth in China and the United States weakened the demand outlook.
Brent crude futures was down $2.56 to $99.81 a barrel by 1410 GMT, in trade which saw it fall below $100 for the first time since April 23.
The contract lost seven percent in April, its biggest monthly drop in 11 months on the back of indicators suggesting the global economy remains in a fragile state.
"Oil is extending the weakness that we saw yesterday. The market sentiment is being weighed down by poor activity indicators in China and the United States," said Harry Tchilinguirian, head of commodity market strategy at BNP Paribas.
U.S. oil was down $2.50 at $90.96 a barrel, falling below its 50-day moving average, a key technical indicator watched by traders.
Growth in China's manufacturing sector unexpectedly slowed in April as new export orders fell, raising fresh doubts about the strength of the economy after a disappointing first quarter.
"It's the same picture of relative slow demand," Olivier Jakob, an analyst at Petromatrix, said.
In the United States, the pace of manufacturing growth slowed in April as the sector expanded only modestly, an industry report showed, adding to signs the economy cooled as the second quarter got underway.
The private-sector jobs sector growth also came below market expectations, two days before the government's closely watched nonfarm payrolls data.
A two-day Federal Reserve committee meeting also wraps up on Wednesday, and the Fed is widely expected to maintain its stimulus policy to support an economic recovery that is still too weak for the job market to truly heal.
"There are going to be important macro movements over the next two days with the Fed and the ECB (European Central Bank) meeting tomorrow," Jakob said.
The ECB is widely expected to cut interest rates to a new record low of 0.5 percent after data on Tuesday showed inflation in the euro zone had fallen to a three-year low and unemployment had hit a record of 12.1 percent.
Fundamentals also appeared bearish.
Data from the American Petroleum Institute on Tuesday showed U.S. crude stocks rose by 5.2 million barrels, larger than a forecast 1 million barrel increase.
The more closely watched report from the Energy Information Administration (EIA) will be released at 1430 GMT.
Supply from the Organization of the Petroleum Exporting Countries is predicted to average 30.46 million barrels per day (bpd)in April, up from 30.18 million bpd in March, a Reuters survey showed.
Saudi Arabia's energy minister said on Tuesday the kingdom did not plan to expand its oil production capacity to 15 million barrels per day, dispelling a suggestion put forth by a member of the royal family.
The Buzzard oilfield in the North sea, an important contributor to the Brent crude benchmark, was on schedule to restart later on Wednesday, trade sources said, after a steam release caused the field to be shut down on Monday. (Additional reporting by Aaron Sheldrick and James Topham in Tokyo; editing by William Hardy)