Oil prices plunged more than 10% to multi-year lows on Friday as OPEC's allies rejected additional production cuts that the organization proposed Thursday.

U.S. West Texas Intermediate crude slid 10.07%, or $4.62, to settle at $41.28, its lowest level since Aug. 2016. It was WTI's worst day since Nov. 28, 2014. Earlier in the session WTI traded as low as $41.11 per barrel.

International benchmark Brent crude slid 9.4% to settle at $45.27 per barrel. Its session low was $45.18, which is a price not seen since June 2017.

The meeting between OPEC and its allies, known as OPEC+, concluded with no deal on additional production cuts. The cartel and its allies agreed to meet again to monitor the situation. The current production cuts will be in place until the end of March as planned, but it's uncertain if they will extend beyond this month.

Russian Energy Minister Alexander Novak told reporters leaving the meetings in Vienna on Friday that it meant that members could now pump what they liked starting April 1.

"We have made this decision because no consensus has been found of how all the 24 countries should simultaneously react to the current situation. So as from April 1, we are starting to work without minding the quotas or reductions which were in place earlier but this does not mean that each country would not monitor and analyse market developments," he said.

On Thursday, OPEC recommended additional production cuts of 1.5 million barrels per day from the beginning of next month until the end of the year.

The proposal was conditional on support from non-OPEC producers, including Russia. OPEC cautioned that the deal could only be applied on a pro-rata basis with core members set to cut 1 million barrels per day and non-OPEC partners expected to cut 500,000 barrels per day.