WASHINGTON, Jan. 28 (Xinhua) -- The United States on Monday slapped sanctions on a state-owned oil firm in Venezuela.

The sanctions on Petroleos de Venezuela, S.A., or known as PDVSA, will block 7 billion U.S. dollars in assets and could result in 11 billion dollars in lost sales over the next year, U.S. National Security Adviser John Bolton told reporters at a White House briefing.

Washington's tough sanctions came days after it recognized the opposition leader Juan Guaido as Venezuela's interim president, denouncing incumbent President Nicolas Maduro who won the elections last year with over two thirds of the votes.  The U.S. Treasury described PDVSA as "a primary source of Venezuela's income and foreign currency" in a statement released later in the day, saying that the blacklist could help "prevent further diverting of Venezuela's assets by Maduro."

The Treasury declared that the path to sanctions relief is "through the expeditious transfer of control to the Interim President or a subsequent, democratically elected government."

U.S. Treasury Secretary Steven Mnuchin said in the statement that the United States will "continue to use the full suite of its diplomatic and economic tools to support" Guaido, head of the National Assembly, who declared himself interim president during an anti-government rally.

Maduro was elected in the May presidential elections with 67.84 percent of the votes, and he was sworn in as president on Jan. 10 for another six-year term. On Jan. 23, Guaido, 35, declared himself interim president.

United Nations Secretary-General Antonio Guterres has urged all relevant actors to lower tensions and commit to dialogue to address the protracted crisis in Venezuela, after anti-government protests in the capital Caracas turned violent, said his spokesman on Thursday.

Xinhua