The price of Brent crude oil dropped below $57 a barrel on Friday, after indications of no slowdown in US oil production.
Reuters reported that Brent declined 30 cents to $56.78, and US crude dropped 20 cents to settle at $46.85.
The International Energy Agency said in its monthly oil market report, "Behind the facade of stability, the rebalancing triggered by the price collapse has yet to run its course, and it might be overly optimistic to expect it to proceed smoothly.
"Yet US supply so far shows precious little sign of slowing down. Quite to the contrary, it continues to defy expectations."
The IEA said worldwide supply increased by 1.3 million barrels per day (mb/d), year on year to an estimated 94mb/d in February, led by a 1.4mb/d gain in non OPEC output.
Declines in the US rig count have yet to dent North American output growth. Final December and preliminary current-quarter data show higher than expected US crude supply.
News of a potential agreement to end a strike by US refinery workers helped support oil prices.
Investors are also observing developments in Libya, where violence between rival militias has affected three-quarters of oil production.