Brent crude oil climbed above $66 a barrel to its highest this year as OPEC-led supply cuts and this week's announcement of a higher than expected cut by Saudi Arabia encouraged investors.
The international oil benchmark ended Friday's session $1.68 higher at $66.25 a barrel, up 2.6 percent on the day. Brent set a fresh three-month closing high going back to Nov. 19 on Friday and rose 6.7 percent on the week.
U.S. West Texas Intermediate crude futures rose $1.18, or 2.2 percent, to $55.58 per barrel, also the best settlement since Nov. 19. WTI ended the week with a 5.4-percent gain.
OPEC, along with allies led by Russia, made voluntary production cuts beginning last month aimed at tightening the market.