Brent crude fell towards $72 a barrel on Friday, close to a four-year low touched the day after OPEC decided not to cut oil output to support prices.
OPEC's decision, which came after Saudi Arabia blocked calls from poorer members of the Organization of the Petroleum Exporting Countries to cut, led to a rout in oil prices on Thursday.
"The move aligns with Saudi Arabia's stance to allow the oil market to stabilise itself and be driven by supply and demand fundamentals," ANZ analysts said in a note on Friday.
Brent crude had fallen 13 cents to $72.33 a barrel by 0211 after plummeting $5.17 to close the previous session at 72.58. Earlier on Thursday, it touched its weakest since July 2010 at $71.25.
The crude benchmark is headed for its steepest monthly decline since November 2008, after falling more than 15% this month.
Brent has lost more than 37% since June when it hit $115.71 a barrel, hurt as increasing shale production in North America created an oil glut amid sluggish global economic growth.
US crude for January delivery plunged $4.86 to $68.83 a barrel, after dropping to its lowest since May 2010 at $67.75 in early Asian trade. U.S. markets were shut on Thursday for the Thanksgiving holiday.
US crude has shed almost 15% in November, its biggest monthly drop since May 2012.
OPEC's decision marked a "watershed" for oil markets, Barclays analysts said in a note.
"In keeping the production target at 30 million barrels per day, OPEC is clearly signaling that it will no longer bear the burden of market adjustment alone and this decision puts the onus on other producers, especially U.S. tight oil to adjust as well," they said.
Russia's most powerful oil official Igor Sechin said oil prices could fall to $60 or below by the end of the first half of next year and that Russia had the potential to cut between 200,000 and 300,000 barrels a day of production if prices remained low.
Responding to OPEC's decision, Venezuela president Nicolas Maduro said the country would keep campaigning until oil prices rebounded to $100 per barrel.
A further blow to global oil demand could come on Monday when China releases official Purchasing Managers' Index (PMI) date for November which could show slower growth, according to a Reuters poll.