Oil futures rose sharply early Friday, trading at their highest since October with support tied to cold weather in the U.S. and elsewhere and supply concerns.

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

Oil prices jumped more than 4% on Friday, with global benchmark Brent breaking $80 per barrel for the first time since October on fears that tougher U.S. sanctions on Russia will disrupt crude supplies.

Oil prices fell on Thursday, extending losses from the previous day, pressured by large builds in U.S. fuel inventories last week, though concerns over tighter supplies from OPEC members and Russia capped the decline.

U.S. crude oil inventories fell for a seventh consecutive week, while product stocks saw large builds last week as refineries increased their capacity use.