WASHINGTON (Reuters) - The United States believes Iran's breakout time to producing enough highly enriched uranium for one nuclear weapon is now "really short" and alarming, a senior Biden administration official told reporters on Friday.

       The official, speaking on condition of anonymity, did not have a precise time for the breakout, which has been estimated to be a matter of months.

       "But it's really short. It is unacceptably short," the official said, calling it "alarming".

       The official said Andrea Gacki, the Treasury Department's director of foreign asset control, was in the United Arab Emirates earlier this week urging private companies not to evade sanctions against Iran.

       "If you are evading sanctions, the U.S. will have its eye very much on you. There will be consequences," the official said.

       (Reporting by Steve Holland; editing by Jonathan Oatis)