(CNN)-- Iran's Supreme Leader, Mojtaba Khamenei, stated that 'revenge' is necessary for the killing of his father, Ali Khamenei, at the hands of the United States and Israel.

In a statement attributed to him and carried by the semi-official Fars News Agency, he said: 'Revenge is the demand of our nation, and it must definitely be carried out.'

The statement added, addressing the late leader: 'We pledge that we will avenge your pure blood and the blood of all martyrs of these two wars from the criminal murderers stained with shame. These criminals – whose names are known and documented from the highest to the lowest – will take with them to the grave their wish to die peacefully in old age in their beds. And they must realize that this matter does not depend on my presence or the presence of other officials.'

This warning came just hours after US President Donald Trump threatened to 'crush' Iran if it tried to kill him.

The new Supreme Leader has not appeared publicly since his appointment.