Oil prices rose more than 1 percent on Thursday, on track for a fourth straight day of gains, but analysts remained cautious about record-high U.S. crude inventories.
Brent crude futures gained 58 cents, or 1.07 percent, to $54.94 a barrel. U.S. West Texas Intermediate (WTI) crude futures rose 1.08 percent, or 55 cents a barrel to $51.70. WTI touched a session high of $51.82 a barrel on Thursday.
The gains put crude on track for its best close since a March 8 rout when investors bailed out of bullish positions due to concerns about supply.
Crude prices have been rebounding from a sharp decline in March. Refinery runs are starting to increase as U.S. summer driving season approaches and gasoline inventories have been declining.
Yet U.S. government data still show crude inventories at record levels, prompting some analysts to grow concerned about speculators jumping back into the market after several weeks when they reduced positions in response to inventory figures.