Oil prices retreated further Friday as data showed that the U.S. rig count increased for the second straight week.
The number of rigs operating in U.S. fields rose by 3 to 328 this week, said oilfield services company Baker Hughes Friday. Last week, the rig count rose by 9 rigs. At this time last year, drillers had 635 oil rigs online.
Meanwhile, a stronger U.S. dollar continued to weigh on investor sentiment, which made the dollar-denominated oil less attractive for holders of other currencies.
The dollar index, which measures the greenback against six major peers, was up 0.66 percent at 94.576 in late New York trading Friday.
The West Texas Intermediate for July delivery dropped 1.49 U.S. dollars to settle at 49.07 dollars a barrel on the New York Mercantile Exchange, while Brent crude for August delivery lost 1.41 dollars to close at 50.54 dollars a barrel on the London ICE Futures Exchange.