The price of Brent North Sea crude oil for delivery in November rose 63 cents to $43.08 in pre-opening electronic trading, the highest level since 23 August, traders said on Monday.
On the New York Mercantile Exchange, light sweet crude for October delivery climbed 60 cents to $46.19 in electronic deals.
"Prices are up because of Yukos and the US stocks (supplies)," GNI Man-Financial trader Robert Laughlin said.
"The US stocks are a big concern as there is still news that oil imports in the US could be disrupted by the hurricane."
Further falls feared
The US Energy Department reported last week that crude oil inventories tumbled by 7.1 million barrels to 278.6 million in the week to 10 September, reaching the lowest levels in nearly seven months.
Traders fear further falls in the wake of Hurricane Ivan. Crude oil futures shot higher on Friday as traders assessed the impact of Hurricane Ivan on supplies in the US Gulf coast.
In New York, oil prices have
surged $1.71 to $45.59
In New York, prices surged $1.71 to $45.59, closing above $45 for the first time in nearly a month. Brent North Sea crude rose by $1.70 to $42.45.
There were worries that tropical storm Jeanne - which has killed at least 50 people in Haiti - could further disrupt US supplies.
"Tropical storm Jeanne is now heading for the [US Gulf] region
and could further delay imports," said analysts at the Sucden brokerage firm.
China's oil deliveries
As for Yukos, "the fear of the market is that the problem could spread to other countries than China and we could see the end of Yukos as we know it. The market is very nervous," Laughlin said.
Yukos partially halted deliveries to China because its legal troubles have left it without cash to pay transport and customs costs, Russia's Interfax news agency reported on Sunday.
"The fear of the market is that the problem could spread to other countries than China and we could see the end of Yukos as we know it"
GNI Man-Financial trader
Russia's oil giant has suspended exports to the China National Petroleum Corporation, to which it was due to deliver one million tonnes before the end of the year, a Yukos spokesman told the agency, saying the "temporary measure" was authorised by the firm's executive board over the weekend.
Yukos, the largest oil producer in Russia, has been the sole provider of Russian oil to China, but the company's financial difficulties have raised doubts about its capacity to continue.
The firm's oil represents roughly 7% of Chinese consumption at 400,000 barrels per day.