Iran's stock of uranium close to weapons grade has jumped since December, two reports by the U.N. nuclear watchdog said on Wednesday.

Iran has accelerated its production of near weapons-grade uranium as tensions between Tehran and Washington rise after the election of U.S. President Donald Trump, a report by the United Nations’ nuclear watchdog seen by The Associated Press on Wednesday showed.

Iran’s stockpile of uranium enriched just below the level needed for nuclear weapons surged more than 50% in the last three months, defying mounting pressure on the Islamic Republic to curb its atomic activities.