State media in the Islamic republic said Monday it had started the process of enriching uranium to 20 percent purity at its Fordow facility, going well beyond the threshold set by the 2015 nuclear deal.

Netanyahu said in a statement that the move "cannot be explained in any way except as the continued realisation of its intention to develop a military nuclear programme".

"Israel will not allow Iran to manufacture nuclear weapons," he added.

Israel, widely believed to be the only nuclear-armed country in the Middle East, has long asserted that Tehran is trying to acquire its own nuclear arsenal and that it seeks the destruction of the Jewish state.

Netanyahu argued long and fiercely against the 2015 deal between Iran and world powers for the lifting of international sanctions in return for it freezing what it says is a peaceful nuclear programme.

But in 2018, US President Donald Trump pulled the United States out of the agreement and reimposed sanctions, prompting Iran to roll back its own commitments.