Oil prices tumbled more than 2 percent on Friday, marking the biggest weekly drop in a month, on renewed concerns that increasing U.S. production and high inventories will thwart OPEC's attempts to reduce the global crude glut.
U.S. crude futures fell below $50 a barrel for the first time in two weeks, with volumes picking up in an active session that by late afternoon showed more than 560,000 front-month contracts changing hands, more than the daily average.
U.S. crude futures, which rolled over on Friday, settled at $49.62 a barrel, down $1.09, or 2.2 percent. For the week, it was down 6.7 percent, its steepest drop since the week of March 10.
Brent futures were down $1.05, or 2 percent, at $51.94 a barrel by 2:38 p.m. (1838 GMT), on pace for a roughly 7 percent weekly decline.
Saudi Arabia and Kuwait, key members of the Organization of the Petroleum Exporting Countries, favor extending their production-limiting deal with non-member producers into the second half of the year.