A policeman walks past the car belonging to Iranian nuclear scientist Mostafa Ahmadi-Roshan at a blast site outside a university in northern Tehran. -Reuters Photo

JERUSALEM: A senior Israeli official on Wednesday gave a cryptic reaction to a car bomb which killed an Iranian nuclear scientist, saying he was unaware who did it but calling it an act of “revenge.”

”I don't know who took revenge on the Iranian scientist, but I am definitely not shedding a tear,” Israeli military spokesman Brigadier General Yoav Mordechai wrote on his official Facebook page.

Mostafa Ahmadi Roshan, 32, was killed along with his driver/bodyguard in a Tehran car bombing earlier on Wednesday, in a blast the Islamic republic immediately blamed on Israel and the United States.

He was the fourth Iranian scientist to be killed in an explosion in the past two years, with the finger repeatedly pointed at Israel.

Israeli officials rarely respond to such accusations and for the most part, do not comment on events in Iran, but the story made the headlines on the websites of the country's main newspapers, as well as on its radio and television stations.

The blast came a day after Israel's chief of staff said 2012 would be a “critical” year for Iran.

“2012 is expected to be a critical year in terms of the link between the continuation of the nuclearisation (process), the internal changes within the Iranian leadership, the growing pressure from the international community and things which happen to them in an unnatural way,” Lieutenant General Benny Gantz told MPs in remarks communicated by a spokesman.

His comments were interpreted in the press as referring to a series of mysterious attacks targeting Iran's nuclear programme and officials involved in various aspects of it.