Oil prices have dropped to the lowest level so far in 2017 on Thursday.
Brent crude, the international benchmark, fell below $50 a barrel to $49.69. US marker West Texas Intermediate dropped to $46.73 a barrel.
Both benchmarks are now at levels last seen in November, having erased virtually all the gains since Opec agreed a deal to curb supplies in a bid to end the worst oil crash in a generation.
The oil cartel’s attempts to reinforce the market have been hit by a quick rebound in US shale production and by signs Opec exports have not fallen as fast as some expected, despite a high degree of compliance by members with the actual production cuts.
Thursday’s price moves came a day after US energy department data showed US crude inventories fell by less than expected last week.