Oil fell in price by $US1 per barrel on Wednesday after crude inventories in the United States reached their highest level in nearly two years.
The Energy Information Administration said crude oil stocks rose by 2 million barrels to 353.3 million last week. Gasoline supplies jumped by 3.2 million barrels.
US light crude fell $US1.02 to settle at $US48.14 per barrel. London Brent crude was down 58 cents to settle at $US47.66 per barrel.
A steep drop in oil prices since they reached $US147.27 on 11 July last year, has pushed the Organization of Petroleum Exporting Countries to make production cuts of 4.2 billion barrels per day since September.
On Sunday, the cartel promised stricter enforcement of existing curbs.