Oil prices closed higher Tuesday amid concerns about the escalating tensions between Iran and the West over Tehran's nuclear program.
New York's main contract, light sweet crude for delivery in January, closed 29 cents higher at $100.28 a barrel.
In London, Brent North Sea crude for January jumped $1.02 to settle at $110.81 a barrel.
"There is a lot more risk on the table," said Bart Melek at TD Securities.
"Tensions between Iran and Western countries are increasing" and could make oil a serious issue, "especially if they (the West) decide to block the Hormuz Strait."
Iran borders the strategically sensitive Strait of Hormuz that links the Gulf with the Gulf of Oman and through which much of the region's oil is transported.
Australia expanded sanctions against Iran Tuesday to restrict business with the country's petroleum and financial sectors as concern mounts over the country's suspected nuclear weapons program. Tehran insists its nuclear program is for civilian purposes.
Britain, Canada and the United States slapped fresh sanctions last month on Iran following a United Nations agency report that strongly suggests the country is researching nuclear weapons.
The European Union followed suit by expanding a blacklist against Iranian firms and individuals, although Iran has dismissed the UN report as baseless.
