A warning by the Organisation of the Petroleum Exporting Countries that the world remains oversupplied also dampened sentiment as key producer nations prepared to gather in Doha for Sunday's talks on freezing output.
At around 0250 GMT, US benchmark West Texas Intermediate for delivery in May was down 47 cents, or 1.13 per cent, at USD 41.29 and Brent crude for June dropped 48 cents, or 1.09 percent, to USD 43.70 a barrel.
Prices shot to 2016 highs Tuesday on the back of news that OPEC kingpin Saudi Arabia and non-OPEC producer Russia had reached a consensus to freeze output, stoking hopes of a wider deal in Doha.
EY oil and gas analyst Sanjeev Gupta said the "bearish" US inventory data helped push down prices as it signals weaker demand in the world's top oil consumer.
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"In the meantime, China's first-quarter economic data due tomorrow (Friday) and results of the Doha meeting will set the tone for near-term price development," Gupta told AFP.
The US Energy Information Administration on Wednesday said US commercial crude stockpiles jumped 6.6 million barrels, or more than six times what analysts had expected.
Prices slumped by about three quarters to below USD 30 between mid-2014 and February this year on the back of the global supply glut and overproduction.