Twin blasts in Iran's capital killed a prominent nuclear scientist and wounded another on Monday, said state media reports that promptly accused Israeli agents on motorbikes of attaching the bombs to their cars.
Iranian students walk past maps during an exhibition of nuclear industry achievements at the Shahid Beheshti University, north of Tehran.
"In a criminal terrorist act, the agents of the Zionist regime attacked two prominent university professors who were on their way to work," the website of Iran's state television network reported, referring to archfoe Israel.
"Dr. Majid Shahriari was killed and his wife was injured. Dr. Fereydoon Abbasi and his wife were injured," the report said.
Fars news agency said the scientists were targeted in two different locations by men on motorcycles who approached their vehicles and attached bombs to their cars.
Shahriari was a member of the nuclear engineering department of Shahid Beheshti University in northern Tehran, according to the official IRNA news agency.
Abbasi held a PhD in nuclear physics and did nuclear research at the defence ministry, the hardline news website Mashreghnews said.
The 52-year-old was "one of the few specialists who can separate isotopes," and had been a member of the elite Revolutionary Guards since Iran's Islamic revolution in 1979.
Shahriari was a researcher in the SESAME project, or Synchrotron-light for Experimental Science and Applications for the Middle East, a regional organisation for scientific cooperation, other reports said.
In January, Masoud Ali Mohammadi, another Iranian nuclear scientist involved with the SESAME project, was killed in a bomb attack which Tehran blamed on "mercenaries" in the pay of Israel and the United States.
"The issue of the assassination of two Shahid Beheshti University professors is currently under investigation and its results will be announced," deputy Tehran governor Safar Ali Baratlu told ISNA news agency.
"These assassinations were not personal and I think these assassinations are different from the previous assassinations, but we are still investigating it," he said.
The reported attacks came a day after the top US military officer said the United States, which is suspicious of Iran's nuclear drive, was weighing military options in the face of Tehran's announcement it had an atomic power plant up and running.
"We've actually been thinking about military options for a significant period of time," Admiral Mike Mullen, chairman of the US joint chiefs of staff said in an interview with CNN.
Mullen said he doesn't believe that Iran's nuclear plant is for civilian use "for a second."
"In fact, the information and intelligence that I've seen speak very specifically to the contrary. Iran is still very much on a path to be able to develop nuclear weapons, including weaponizing them, putting them on a missile and being able to use them," he said.
On Saturday, Iran said its first atomic power plant built by Russia in the southern city of Bushehr had begun operations, ahead of a new round of talks with Western powers over the country's controversial nuclear drive.
The attacks also come hot on the heels of the release on Sunday of diplomatic cables by the whistleblower website WikiLeaks that revealed Saudi Arabia's king "repeatedly" urged Washington to take military action against Tehran's nuclear programme.
And in July, Iranian nuclear researcher Shahram Amiri said after returning to the Islamic republic that he had been held in the United States for more than a year after being "kidnapped" at gunpoint by two Farsi-speaking CIA agents in the Saudi city of Medina.