Softer-than-expected U.S. service-sector and jobs data sent prices falling as well.
On the New York Mercantile Exchange, light, sweet crude futures for delivery in May traded down 2.18% at USD95.07 a barrel on Wednesday, off from a session high of USD96.94 and up from an earlier session low of USD94.91.
The U.S. Energy Information Administration said in its weekly report that U.S. crude oil inventories rose by 2.71 million barrels in the week ended March 29, well above market forecasts for a gain of 2.20 million barrels.
Total U.S. crude oil inventories stood at 388.6 million barrels as of last week, well above the upper limit of the average range for this time of year.
The U.S. government also reported that total motor gasoline inventories decreased by 572,000 barrels, less than expectations for a decline of 852,000 barrels.
Rising oil inventories cemented growing concerns that the U.S. economy is awash in oil, which sparked a selloff.
Soft U.S. indicators depressed prices as well by stoking concerns that the U.S. economy continues to face headwinds along its recovery and may demand less fuels and energy than once thought.
The Institute of Supply Management reported earlier its non-manufacturing purchasing managers' index fell to 54.4 in March from 56.0 in February.
Analysts had expected the index to decline to 55.8 last month, which weakened the greenback.
Separate industry data revealed that the U.S. private sector added fewer jobs than expected last month.
Payroll processor ADP reported earlier that nonfarm payrolls increased by 158,000 in March, well below expectations for a gain of 200,000, following an upwardly revised increase of 237,000 in February.
The numbers sparked concerns that Friday's official March jobs report may miss earlier expectations for a pickup in job creation.
Elsewhere on the ICE Futures Exchange, Brent oil futures for May delivery were down 2.40% at USD108.03 a barrel, up USD12.96 from its U.S. counterpart.