Oil prices retreated on Friday as US energy companies added oil rigs for the first time in three weeks.
The number of rigs operating in US oil fields increased by two to a total of 862 rigs this week, oilfield service firm Baker Hughes said in its weekly report on Friday, Xinhua reported.
The US oil rig count rose by one in August after gaining three rigs in July and losing one in June.
A stronger US dollar also made the dollar-priced commodity less attractive for holders of other currencies.
The dollar index, which measures the greenback against six major peers, increased 0.35 percent at 95.0540 in late trading.
The West Texas Intermediate for October delivery fell $0.45 to settle at $69.80 a barrel on the New York Mercantile Exchange, while Brent crude for October delivery lost $0.35 to $77.42 a barrel on the London ICE Futures Exchange.