Oil prices reached a record $50 a barrel Monday as Nigeria emerged as the latest focus for worries about supply in an already tight worldwide energy market.

The U.S. light crude front month contract rose a further 36 cents a barrel in after-hours electronic trading to hit $50, its loftiest level in the 21 years of trade on the New York Mercantile Exchange. Light crude for November delivery closed at $49.64 a barrel in regular trading on the New York Mercantile Exchange -- a new Nymex record.

London Brent, the benchmark for European crude imports, settled 60 cents higher at $45.13, after hitting a new record of $46.28 a barrel.

"We now think that (U.S.) crude oil could reach $61 before a meaningful sell-off occurs," investment bank Morgan Stanley said in a report to its clients.

Growing concerns over militancy in Nigeria, OPEC's fifth-largest producer, are compounding worries about supply security in Russia, Saudi Arabia and Iraq.

The effects of several recent tropical storms are also helping to boost prices, as petroleum output in the Gulf of Mexico returns at a slower-than-expected rate after Hurricane Ivan.

''The Ivan damage is persisting,'' said John Kilduff, senior oil analyst at Fimat USA in New York. Kilduff described $50-a-barrel as ''just a mythical sort of number, like the 4-minute mile or 3,000 base hits.''

The United States has lost more than 11 million barrels of oil production in the past two weeks, according to government data, with Gulf of Mexico output still down nearly 500,000 barrels a day. Analysts had initially thought the region's oil production would return to normal about a week after the hurricane. T

The blow to domestic output, while expected to be short-lived, comes as analysts worry about OPEC's inability to swiftly and sharply increase production in the event of a more significant and prolonged supply disruption.

"All these factors create apprehension in the market and reinforce the view that we're on a knife's edge in terms of supply and demand," said Daniel Hynes, industry analyst at ANZ Bank in Melbourne. "The uncertainties heighten the risk premium applied to this market."

Global supplies have risen strongly this year but are still straining to meet the fastest demand growth in 24 years. World crude output is close to its limit after many years when OPEC producers kept large volumes untapped.

The lack of a supply cushion has reinforced the view among some investors that oil near $50 is not overpriced, despite a 50% jump in crude prices since the start of the year.

Source: Agencies