Oil prices leaped Monday as violence intensified in the Israel-Gaza conflict, sparking fresh concern about supplies from the crude-rich Middle East.
The market also found support from prospects that top oil consumer the United States will avoid the so-called "fiscal cliff" of automatic tax increases and spending cuts due in January that risks a return to recession.
New York's main contract, West Texas Intermediate (WTI) for delivery in January, soared $2.36 from Friday to settle at $89.28 a barrel.
In London trade, Brent North Sea crude for January delivery added $2.75, closing at $111.70 dollars a barrel.
"The ongoing conflict between Israel and Palestine, which has stoked fears about supply of oil across the Middle East region, continues to provide the main source of support to prices," GFT Markets analyst Fawad Razaqzada said.
"Also lifting crude oil today was news that Republican and Democratic lawmakers are showing more willingness to find a compromise on the US fiscal cliff, even though major challenges remain."
Briefing.com analysts noted that the WTI contract gained support "from strength in the equities market, Middle East conflict, and a weaker dollar index." A weaker US currency makes dollar-priced oil tends to push up demand for black gold.
A sixth day of Israeli strikes on Monday killed 24 Palestinians, taking the Gaza death toll past 100 as UN chief Ban Ki-moon joined efforts to broker a truce to end the worst violence in four years.
Capital Economics analyst Julian Jessop said traders were concerned over whether Israel would launch a land assault -- and whether key crude producer Iran would be drawn into the conflict.
"The wider issue is the risk that the conflict spreads, perhaps encompassing an Israeli strike on Iran," Jessop said.