Oil prices fell Friday as data showing an increase in US petroleum drilling activity added to worries about excess supply.
Petroleum companies boosted the US oil rig count by 14 for the week ending July 22, the fourth straight week to see an increase, Baker Hughes reported.
The data came on the heels of a US petroleum inventory report Wednesday that showed higher gasoline inventories.
"Crude is heading lower into the weekend as supply glut fears persist, while further endorsement of a sell-off is provided by a stronger dollar," said Matt Smith of Clipper Data.
US benchmark West Texas Intermediate for September delivery shed 56 cents to $44.19 a barrel on the New York Mercantile Exchange.
Brent North Sea oil for September delivery lost 51 cents at $45.69 a barrel in London.
Crude rose to above $50 in June owing to fires in Canada's key oilfields, unrest in key producer Nigeria and the start of the US driving season.
However, with some of those issues now fading, prices have softened again.