LONDON (AFP) - World oil prices bolted to new record summits, reaching 53 dollars in New York on markets nervous about tight global supplies with winter approaching in the northern hemisphere.
Looming strike action in major oil producer Nigeria was adding further support to prices, analysts said.
The price of reference light sweet crude for November delivery spiked at 53 dollars a barrel in opening deals on the New York Mercantile Exchange, the highest level in the contract's 21-year history.
US crude futures later eased to 52.30 dollars, a gain of 28 cents from the day's previous closing price.
In London Brent North Sea crude oil for delivery in November surged above 49 dollars a barrel for the first time, hitting 49.20 a barrel in afternoon trading. It stood at 48.62 dollars in late deals, a gain of 63 cents.
Prices continued their seemingly inexorable rise a day after the US Department of Energy reported a smaller-than-expected rise in US crude oil inventories and a fall in heating oil.
Ongoing supply problems in the Gulf of Mexico were also causing concern.
"There's a lot of concern surrounding the levels of stocks in the US," said Veronica Smart, an analyst at the Energy Information Centre, a British-based consultancy.
"We're approaching winter when demand is obviously higher, particularly for gasoil. If we do have a particularly harsh winter I think supplies could struggle."
In the event of a cold snap, "we could definitely see Brent breaking 50 dollars a barrel and heading further up," she predicted.
Weekly US crude oil and gasoline inventories rose modestly as importers and refiners began to recover from Hurricane Ivan, the Energy Department said Wednesday.
Crude oil inventories in the week to October 1 rose 1.1 million barrels to 274.0 million. Gasoline stocks climbed 600,000 barrels to 199.4 million as refiners were able to boost output after Ivan.
US commercial inventories of distillates -- mostly diesel and heating oil -- fell by 2.1 million barrels to 123.4 million in the week to October 1, the Energy Department said.
Almost 27 percent of the Gulf of Mexico's 1.7 million barrels of daily oil production remains disrupted, according to the US Department of the Interior.
"A smaller than expected build in US crude oil inventory and a counter-seasonal draw in heating oil combined with the continued outage of almost 500,000 barrels per day of Gulf of Mexico crude oil production continues to provide a solid underpinning to the crude oil market," said Barclays Capital analyst Kevin Norrish.
"Threats of a strike by Nigerian oilworkers are also keeping the market on edge," he added shortly before Nigerian labour unions vowed to go ahead with a threatened nationwide general strike to protest against rising fuel prices, threatening to bring the economy of Africa's biggest oil exporter to a halt.
Separately, Nigerian workers for the Anglo-Dutch oil giant Shell launched an unexpected two-day strike on Thursday in protest at planned job cuts, a company spokesman said.
"This morning both unions commenced industrial action in reaction to the implementation of our reorganisation programme," a Shell spokesman said.
"It is to last two days. It has not affected production yet," he added.
Adjusted for inflation, world oil prices remain far below the levels reached in the wake of the 1979 Iranian revolution when prices surged to upwards of 80 dollars a barrel in today's money.
But prices have more than doubled from about 20 dollars a barrel in New York at the start of 2002, surging by about 50 percent since the start of this year.