U.S.' gasoline inventories increased last week, according to the Energy Information Administration (EIA) on Wednesday, and pushed oil prices to their lowest level for the last two and a half months.
Gasoline stocks rose 1.5 million barrels, or 0.7 percent, to reach 237.7 million barrels for the week ending April 14, the EIA said.
The market expectation for gasoline inventories was a decline of 1.9 million barrels last week.
"The rise in output from refineries was also the key reason for the growth in gasoline stocks," Thomas Pugh, a commodities economist at London-based Capital Economics, said in a note.
After the surprise increase in gasoline inventories, oil prices in global markets fell to their lowest level in the last six weeks.
On Wednesday, American benchmark West Texas Intermediate fell to as low as $50.09 per barrel, while international benchmark Brent crude plummeted to $52.58 a barrel.
Meanwhile, the U.S.' crude oil production rose for the ninth consecutive week.
For the week ending April 14, domestic crude output increased by 17,000 barrels per day (bpd) to 9.25 million bpd, according to the EIA.
Oil imports decreased by 68,000 bpd to 7.81 million bpd, during the same period.
By Ovunc Kutlu in New York