Oil prices have ended lower on rising concerns over the extent to which the OPEC (Organization of the Petroleum Exporting Countries) member countries would implement the output cut deal.
OPEC reached an agreement in November to cut oil production to curb a global supply glut that has depressed prices for more than two years, Xinhua news agency reported on Saturday.
Although some countries have promised to implement the deal, there still lacks hard evidence on production reductions.
Investors also worried that the rising US oil supply might offset any reductions, which weighed on the oil prices on Friday.
The Energy Information Administration (EIA) said in its weekly report on Wednesday that the US crude oil inventories rose 4.1 million barrels last week to 483.1 million, up 7.1% from 2016 at this time.
The West Texas Intermediate for February Delivery decreased $0.64 to settle at $52.37 a barrel on the New York Mercantile Exchange, while Brent crude for March delivery erased $0.56 to close at $55.45 a barrel on the London ICE Futures Exchange.