TEHRAN (AFP) - Iran has beefed up security measures to protect its nuclear experts after a top atomic scientist was killed in a bombing this week, Fars news agency reported on Sunday. Some measures have been taken to protect and safeguard nuclear scientists, even though there were some before, but now these measures have been increased, Tehran governor Morteza Tamadon was quoted as saying. Massoud Ali Mohammadi, a particle physics professor at Tehran University, died when a bomb strapped to a motorbike was triggered by remote control as he was leaving his home on Tuesday. Officials in the Islamic republic have accused the CIA and Mossad, the respective intelligence agencies of the United States and Israel, of having a hand in the murder. Tamadon echoed comments made on Thursday by President Mahmoud Ahmadinejad, who said Zionist methods were used in the bombing. Its not like Americans and Zionists (Israelis) would dare to enter our country... Iran would not give them such security and possibility but they have got help from the anti-revolutionaries, monarchists and outcasts, Tamadon said. The governor said Iran had since obtained some leads to chase the case.