World oil prices fell further below $ 50 on Friday -- near levels unseen in more than three years -- on growing fears that a worldwide recession could ravage energy demand, analysts said.
New York's main futures contract, light sweet crude for January delivery, dropped 59 cents to $ 48.83 a barrel.
The December contract plunged $ 4.00 a barrel before ending at a closing price of $ 49.62 on the New York Mercantile Exchange on Thursday. The contract earlier hit an intraday low of $ 48.64, a level last seen in May 2005.
Brent North Sea crude also plunged through the psychological barrier of $ 50 a barrel.
Today the contract was 68 cents lower at $ 47.40 a barrel.
Brent fell as low as $ 47.82 before settling $ 3.64 lower at $ 48.08 in London on Thursday.
Analysts said sentiment was hammered by a dismal unemployment report in the United States, the world's biggest energy consumer.
US unemployment claims surged to a 16-year high, government data showed, offering more evidence the world's largest economy appeared to be sliding into a deep recession.
"The hits to the economy keep on coming... Energy prices were under pressure all night, and the losses have accelerated on the back of the claims data," said John Kilduff, an analyst at MF Global.
Concern for slowing global economic growth and its impact on energy demand has already led oil prices to plummet from record peaks above $ 147 in July.