Brent crude was down 19 cents, or 0.4%, at $45.20 a barrel by 10:52am EDT (2:52pm GMT).

US WTI crude slipped by 5 cents to $42.97 percent per barrel.

The US government is expected to report on Wednesday a 1 million-barrel crude stockpile drawdown for the week ended 5 August, after unexpected rises in two prior weeks, analysts polled by Reuters said.

The American Petroleum Institute (API) will issue its own report on US petroleum stockpiles after Tuesday's market settlement, at 4:30pm EDT (8:30pm GMT).

The forecast US draw aside, analysts and traders have mostly cautioned of a glut building in both crude and refined oil products this summer, with US gasoline demand particularly lagging supply despite the peak season for driving in the US.

Opec's biggest producers have also been pumping near record high levels.