Oil prices pulled back sharply on Friday, after earlier rising on expectations that OPEC and its allies would agree to cut output next month.

Prices remain under pressure on concerns that the global market is oversupplied, with benchmarks posting a sixth straight weekly loss. An oil market sell-off has shaved more than a fifth off the Brent crude benchmark and slashed the price of U.S. crude by 25 percent since early October.

Brent 14 cents higher at $66.76 a barrel on Friday, after earlier rising more than 2 percent. It has been recovering for three sessions since hitting an eight-month low on Tuesday but still ended the week nearly 5 percent lower.

U.S. West Texas Intermediate crude futures ended Friday's session flat at $56.46 a barrel, briefly turning negative and falling $1.50 from the session peak. WTI logged its steepest one-day loss in more than three years on Tuesday. The contract fell 6.2 percent this week.

Ministers from the Organization of the Petroleum Exporting Countries meet on Dec. 6 in Vienna to decide on production policy for the next six months. They have to decide what to do about a growing surplus in world markets.