Updated

Oil prices edged up above $99 Thursday, the first trading day after Christmas, as violence in South Sudan stoked concerns about the country's oil production.

Benchmark U.S. oil for February delivery was up 17 cents to $99.39 a barrel in electronic trading on the New York Mercantile Exchange.

The contract inched up 31 cents to close at $99.22 on pre-Christmas Tuesday after briefly dropping below $99.

Oil prices gained nearly 3 percent last week as optimism about the U.S. economic recovery lifted expectations for the country's energy demand.

Worries over instability in South Sudan have led some analysts to predict the contract may top $100 a barrel for the first time since mid-October. On Tuesday, the U.N. Security Council voted to increase U.N. peacekeeping forces in conflict-torn South Sudan by nearly 80 percent.

Brent crude, a benchmark for international oils, was up 11 cents at $112.01 a barrel on the ICE exchange in London.

In other energy futures trading on Nymex:

— Wholesale gasoline rose 0.31 cent to $2.8165 a gallon.

— Heating oil inched up 0.4 cent at $3.0725 a gallon.

— Natural gas was up 3.1 cents to $4.447 per 1,000 cubic feet.