LONDON (AFP) -- World crude prices dropped further on Friday as worries over output eased in major oil producers Norway and Nigeria, traders said.

New York's main contract, light sweet crude for delivery in December, fell 36 cents to 60.00 dollars per barrel in electronic deals before the official opening of the U.S. market.

In London, Brent North Sea crude for December delivery shed 48 cents to 60.29 dollars per barrel in electronic trading.

The contracts had closed down more than a dollar Thursday on profit-taking. It came after crude futures had jumped more than two dollars on Wednesday owing to renewed supply concerns as U.S. heating stocks are falling ahead of the northern hemisphere winter.

On Friday meanwhile, Norway's leading oil company Statoil resumed production at its Snorre A platform in the North Sea after a two-week halt caused by safety problems. Norway is the world's third biggest exporter of oil.

And in Nigeria, Africa's largest producer of oil, protesting youths left three flow stations of the Anglo-Dutch oil group Shell on Thursday which they had occupied since Tuesday.

Production was "very likely" to restart there Friday, Shell officials told AFP.

Oil prices "have gone up and down but remain around 60 dollars and in the short-term it will be around that level", said Victor Shum, an analyst for Purvin and Gertz in Singapore.

The 11-nation OPEC cartel meanwhile promised a week ago to reduce output by 1.2 million barrels a day as crude prices hovered about 25 percent lower than record highs above 78 dollars reached in July and August.