West Texas Intermediate futures for September delivery slid to $47.20 (-0.40%), while Brent crude fell to $53.13 (-0.64%). Prices approached four-month lows as renewed declines in Chinese stocks intensified investors' concerns over prospects of global economic growth and demand for oil.

Some analysts believe that crude prices will edge up by the end of the current year, although they will still be quite low.

Investors are waiting for weekly data on U.S. inventories.