(JTA) — Iran arrested 20 suspects who are accused of being involved in the assassinations of three nuclear scientists.

Sunday’s official information about the arrests announced last week was made by Intelligence Minister Heidar Moslehi, according to the Islamic Republic News Agency, Iran’s official news agency.

The arrests on June 14 were made “in various regions and through timely and blitz operations,” the Iranian Intelligence Ministry said last week.

At least five nuclear scientists have been assassinated in the past two years. Iranian officials have said they believe Israel and its Mossad intelligence agency were behind the assassinations.

In May, Iran executed a man convicted of spying for Israel and of assassinating an Iranian nuclear scientist. Majid Jamali Fashi, 24, was sentenced to death in August 2010 for the murder of Ali Mohammadi, a particle physics professor at Tehran University killed by a remote-controlled bomb in a January 2010 attack.

In April, more than 15 Iranian and foreign nationals reportedly were arrested for carrying out alleged terrorist missions for Israel in Iran, according to IRNA. The group was accused of spying for Israel, the attempted assassination of an Iranian expert and sabotage.