Oil prices fell sharply in thin, volatile trading this evening, on course for their first weekly loss in four weeks as the dollar shifted higher.
Oil prices rose early in the session, after US Federal Reserve chairman Ben Bernanke signalled that the central bank was likely to pump more money into the US economy.
But this evening, US crude was down $1.40 to $81.29 a barrel, while Brent dropped $1.64 to $82.56.
The dollar weakened after Bernanke's statement but rallied later on the view that quantitative easing was already priced in. A stronger dollar makes commodities like oil more expensive for buyers holding other currencies.
Meanwhile, OPEC's secretary general said oil prices of $75-$85 a barrel would not hold back the global economy. Some members have called for higher prices to compensate for a weak US dollar. OPEC decided on Thursday to leave its oil output policy unchanged, as it has done since agreeing to a record output cut in December 2008.
