Oil fell to fresh lows not seen since May 2009 on Friday with U.S. crude prices slipping below $58 a barrel on concerns over a global supply glut and weak demand.
U.S. WTI crude settled down $2.14 at $57.81 per barrel, the lowest since May 2009. The contract has lost about 11 percent this week.
Brent crude was down nearly $2 at $62 per barrel and earlier hit a low of $61.35—the lowest since July 22, 2009.
Down 33 percent already, it is on track for its biggest quarterly drop since the fourth quarter of 2008. Brent is down more than 9 percent this week, taking its fall since a June peak above $115 to 45 percent.
The International Energy Agency (IEA) said oil prices would likely come under further pressure, cutting its outlook for demand growth in 2015 and predicting that non-OPEC output gains would increase global supplies.
The IEA, which coordinates the energy policies of industrialized countries, cut its outlook for global oil demand growth for 2015 by 230,000 barrels per day (bpd) to 900,000 bpd on expectations of lower fuel consumption in Russia and other oil-exporting countries.
"It spells out the main scenarios that are in the market and said that stockpiles will be substantially bigger in the first half of 2015," said Bjarne Schieldrop, chief commodity analyst for SEB in Oslo.