Oil prices dropped Friday as worries about a global crude glut continued to weigh on prices.

　　US oil companies added more oil rigs this week despite the collapse in crude prices.

　　Data showed a weekly rise of 21 in the number of active US oil drilling rigs to 659, according to oil services company Baker Hughes' Friday report.

　　US crude supplies of last week added 2.5 million barrels to 463.89 million, according to the weekly report of Energy Information Administration (EIA) released Wednesday. Inventories at Cushing, Oklahoma, the delivery point for the US contract, rose by 813,000 barrels.

　　And the stronger US Dollar made the dollar-priced oil less attractive and more expensive to investors holding other currencies.

　　The US dollar climbed against most major currencies Friday as investors were awaiting the closely-watched Federal Reserve meeting next week, in hope of further rate-hike signals.

　　The West Texas Intermediate for September delivery moved down 31 cents to settle at 48.14 US dollars a barrel on the New York Mercantile Exchange, while Brent crude for September delivery decreased 65 cents to close at 54.62 dollars a barrel on the London ICE Future Exchange.