West Texas Intermediate futures for October delivery slid to $44.02 (-0.29%), while Brent crude fell to $47.26 (-0.67%) ahead of a closely-watched weekly report from the U.S. Energy Information Administration.

Analysts surveyed by Bloomberg expect a 250,000 barrels rise in U.S. crude inventories in the week to September 4.

Meanwhile weak economic data from such Asian countries as China and Japan intensify concerns over the global economic growth and demand for oil at times of global supply glut.