Oil sold off for a second day as falling stock markets and a weak US retail sales report added to concerns about global energy demand.
In morning trading in New York, benchmark oil for May delivery was down $3.07, or 3.3%, to $90.44 a barrel, a one-month low. Oil fell $1.13 yesterday.
OPEC, the US Energy Department and the International Energy Agency, which represents a group of oil-consuming nations, all lowered their outlook for global oil demand this week.
The IEA on Thursday dropped its forecast for demand this year by 45,000 barrels to 90.6 million barrels a day.
Today, stock markets in Asia, Europe and the US petered out at the end of an otherwise strong week.
US government reports also raised concerns about the economy. Sales at US retailers fell 0.4% in March.
And companies restocked their shelves at a much slower pace in February than in the month before.
Brent crude, which sets the price of crude used by many US. refineries to make gasoline, was down $2.98, or 2.9%, to $101.40 a barrel on the ICE Futures exchange in London.
Brent has dropped about 14% in the past two months amid Europe's ongoing financial crisis, increased supplies and tepid forecasts for demand.