Brent oil rose for a fifth straight session on Monday to settle at a six-month high as cold weather in Europe boosted heating fuel demand and pushed the crude's premium to US oil to the highest since November.
European gasoil led gains across the oil complex, rising more than 3.5% as bitter weather killed another 33 people in Europe.
Italy announced it would allow electricity providers to fire up oil-fueled generators to limit natural gas after six-straight days of reduced supplies from Russia.
Additional support for Brent came amid supply concerns from Opec members Iran and Nigeria.
"The cold weather is giving us a lift in the products and that is feeding through to Brent," said Rob Montefusco, a trader at Sucden Financial in London. "Also, any sort of trouble in West Asia is likely to keep Brent well bid."
US crude fell, however, dragged down by concerns about weak consumption and rising inventories that increased the contract's discount to Brent to more than $19 a barrel from more than $2, the largest discount since November.
Traders said the premium could blow out levels eclipsing those seen last year over $28 a barrel as Midwest refinery turnarounds and rising pipeline flows boost inventories in the region, home to the Cushing, Oklahoma, delivery point to the New York Mercantile Exchange's oil futures contract.
Brent March crude rose $1.35 to settle at $115.93 a barrel, highest close since August 2. Monday's trade ranged from $113.65 to $116.22. The $116.22 was the highest since $116.48 intraday on November 8.
US March crude fell 93 cents to settle at $96.91 a barrel, having slumped as low as $96.38.
Heating oil prices traded up nearly 2.3% in late activity, despite forecasts that US total heating demand would run about 14.5% below normal and heating oil demand would be 20.5% below normal.
Trading volumes were heavy, with Brent volume about 22% above the 30-day moving average and US crude about 18% over that average.
The euro weakened against the dollar after the failure of Greek coalition parties to approve the terms of a new bailout package rekindled worries about a chaotic default.
The dollar index edged up and a stronger US currency can pressure dollar-denominated oil by making the commodity more expensive for consumers using other currencies.
Threats to supply
Traders also eyed developments in the West Asia and Nigeria, where a police station was the site of the latest attack by suspected Islamist militants.
Iran's Revolutionary Guards deputy commander said on Sunday that Tehran would target any country used as a launching pad for attacks against its soil. Iran's supreme leader last week threatened reprisals for the West's ban on Iranian oil exports in the standoff over Tehran's nuclear program.
China, the largest consumer of Iranian crude, will halve its crude oil imports from Iran in March versus year-ago levels as a dispute over payments and prices stretches into a third month, oil industry sources involved in the deals said.
Asia's imports of West African crude are at record highs as sanctions on Iran reduce supplies, a Reuters survey of West African flows suggest.
In Syria an explosion ripped through an oil pipeline feeding a main refinery in the city of Homs, the second in a week to hit the pipeline.
New York's main contract, West Texas Intermediate (WTI) light sweet crude for delivery in March, gained 35 cents to $97.26 a barrel and Brent North Sea crude for March delivery advanced 47 cents to $116.40.
"Brent crude rose... As cold weather in Europe boosted heating fuel demand," said Ker Chung Yang, commodity analyst for Phillip Futures in Singapore.
He also told AFP that the WTI was up due to "some bargain hunting" after falling on Monday.
Fatalities from wintry weather sweeping across Europe topped 360 on Monday after snow and rain-swollen rivers burst a Bulgarian dam and killed at least eight people while more homeless perished on frigid city streets.
Switzerland reported temperatures plummeting to minus 35.1 Celsius in the eastern Graubuenden canton.
