Brent crude futures were down $2.36, or 4.8 percent, at $46.44 per barrel by 1:10 p.m. EDT (1710 GMT). The session low was $46.27, the lowest for Brent since May 11.
U.S. crude futures were down $2.23, or 4.7 percent, to $47.20. It earlier hit a two-month low at $44.87.