Oil prices fell more than 2 percent on Monday, pulling back from last week's rally fueled by signs that the global market is starting to rebalance from chronic oversupply.
Benchmark Brent crude futures were down $1.06, or 2 percent, $51.66 a barrel by 2:26 p.m. ET (1826 GMT), after surging more than 3 percent in the previous session.
U.S. West Texas Intermediate crude futures ended Monday's session down $1.14, or 2.4 percent, at $47.37 a barrel. The contract had also risen 3 percent in the previous session.
"We are currently seeing some profit-taking after Friday's strong rally ahead of this week's inventory data," said Hans van Cleef, senior energy economist at ABN Amro.
"Fresh uncertainty about inventories and OPEC compliance (with agreed production cuts) could be enough reason to sell some of the long positions."