Oil prices at high on new worries

US light crude closed at $55.17 a barrel in New York, after having hit $55.50 in trading.
In London, Brent crude went as high as $51.65, before closing at $51.22.
Prices are about 80% higher than a year ago, but would need to hit $80 a barrel in order to surpass the all-time 1981 record in inflation-adjusted terms.
Oil prices have gone up more than $10 a barrel since September.
Disruption fears
"All the demand signals are bullish," said Deborah White, economist at SG Commodities.
"And now we're in winter mode, so stocks have nowhere to go but down."
On Wall Street, US shares fell 1.09% on Friday to close at a new 2004 low as rising crude prices lead to fears consumers and the economy could be affected.
Supply worries stem from an oil production fall in the Gulf of Mexico, where output is still down due to damage from Hurricane Ivan in September.
US Energy Information Administration data on Wednesday showed stocks of heating oil and diesel fuel fell for the fifth straight week.
The world's available oil production capacity is just 1% above daily usage, leaving little room in the event of supply outages.
And further fears of disruption in production in Iraq, Venezuela, Nigeria and Russia continue to influence traders.
China demand
China's increasing appetite for oil imports has also helped pushed prices higher.
Data on Friday showed economic growth has slowed for a third straight quarter in China as government efforts to rein in booming expansion continue to take hold.
But at 9.1% its pace of expansion remains strong, observers say.
"Demand (for oil) is still quite strong and the outlook will depend on how quickly China's economy continues to grow," said analyst Marshall Steeves, from Refco.