Iran said it has made a number of arrests in connection with the murder of two Iranian nuclear scientists, alleging the suspects were spying on behalf of the “Zionist regime” (Israel).

A statement by Iran’s intelligence ministry failed to provide much detail about the people who were arrested.

One the scientists, Mostafa Ahmadi Roshan, who was killed by a car bomb blast in Tehran in January, was a prominent figure in Iran’s much-criticized uranium-enrichment program. The other scientist was Majid Shariari, who was murdered in November 2010.

Over the past two years, five Iranian nuclear scientists have been killed -- Tehran has repeatedly pointed the finger of blame at both Israel and the U.S.