By early afternoon in Europe, benchmark US crude for March delivery was up USD 1.04 to USD 101.34 a barrel in electronic trading on the New York Mercantile Exchange.
Due to the President's Day holiday, the contract's last physical settlement was Friday, when it fell 5 cents to close at USD 100.30.
Severe cold weather in the US has been boosting energy prices. The US East Coast is expected to get more snow, and the cold is extending to other states.
Optimism that China's economy is still healthy after credit growth increased in January also helped lift energy prices.
Meanwhile, a new round of talks began today between Iran and six world powers on finalising a deal to control Iran's nuclear program. The outcome could have an effect on oil prices as Iran is a major oil producer and reduction of sanctions would allow the country to export more of its crude.
Brent crude, a benchmark for international oils, was up 72 cents to USD 109.80 on the ICE Futures exchange in London.
Among other March futures contracts trading on Nymex: Wholesale gasoline rose 3.03 cent to USD 2.8356 a gallon.
Heating oil added 4.08 cents to USD 3.119 a gallon.
Natural gas gained 27.7 cents to USD 5.491 per 1,000 cubic feet.
