Crude prices are having one of their best days in a year, rallying as much as 5% amid concerns that icy weather in the oil patch will crimp domestic supply, while tighter sanctions on Russia and Iran may eliminate barrels from global markets.

The U.S. Treasury Department is sanctioning Russian oil companies, tankers, officials and executives. Oil prices jumped on worries that crude supplies would face disruptions. Oil prices jumped more than 3% on Friday as the U.

The document, purported to be from the U.S. Treasury, was being circulated among traders in Europe and Asia. Reuters could not verify the veracity of the document

The measures include sanctions on Russian oil producers Gazprom Neft and Surgutneftegas, and the blacklisting of 183 vessels involved in Russian energy exports. Dozens of traders, Russia-based oilfield service providers,

Oil prices surged on Friday and were on track for a third straight week of gains as traders focused on potential supply disruptions from more sanctions on Russia and Iran. Brent crude futures gained $1.