Oil prices declined more than 1% following reports of increased crude stock in the US and higher production in Saudi Arabia.
The benchmark US oil price is down 1.93% at $52.94 (£35.58, €48.61) per barrel as at 12.30am ET, after rising to a 2015 high on 7 April. Meanwhile, Brent crude price, the global benchmark, is down 1.42% at $58.26 per barrel.
The US Energy Information Administration (EIA) earlier said crude-oil output in the country that rose to a 42-year high in March would peak in April and May before falling from June to September.
Data from the American Petroleum Institute (API) showed US crude stocks surged 12.2 million barrels last week against analysts' expectations for an increase of 3.4 million barrels.
In addition, Saudi oil minister Ali al-Naimi said that Saudi output would likely remain around 10 million barrels per day after posting a record high of 10.3 million barrels per day in March.
He also noted that Saudi can do nothing to improve oil prices without the support of oil producers outside the Organization of the Petroleum Exporting Countries (Opec).
Therefore, the oil glut on the international market, which led to a plunge in oil prices by a half since June 2014, is expected to remain the same in the short run.
The EIA also said world oil prices could be $5 to $15 a barrel lower than forecast in 2016 if oil-related sanctions against Iran are lifted.
"A lifting of sanctions against Iran should a comprehensive nuclear agreement be concluded could significantly change the forecast for oil supply, demand, and prices," EIA administrator Adam Sieminski said in a statement.