Oil saw its worst monthly drop since the 2008 financial crisis after signs that top producers in the Middle East were continuing to pump at record levels despite a growing global gut.

A higher U.S. oil rig count for a second week in a row added to the market's downside. Uncertainty ahead of key U.S. oil production and rig count data due later in the day also weighed on prices, despite a weaker dollar, which would normally support commodities.