Two car bomb blasts killed one Iranian nuclear scientist and wounded another in Teheran on Monday, Iran's al Alam Arabic language television reported.
The bombings, rare attacks in the Iranian capital, occurred ahead of a possible meeting between Iran and major powers next month to discuss the country's nuclear program.
Analysts say information about Iran's nuclear activities is very valuable for the United States and its allies, particularly ahead of the meeting.
In the past months, Iran has arrested a number of "nuclear spies", warning citizens over leaking information to foreign secret services.
"Majid Shahriyari was martyred and his wife was injured ... Fereydoun Abbasi-Davani and his wife were both wounded," state radio said. "The attackers planted a bomb on each of the teachers' vehicles."
Iran's atomic chief Ali Akbar Salehi warned "enemies" not to play with fire by carrying out such attacks.
"Our nation's patience has a limit ... when it is over our enemies will face a tedious fate," Salehi said. "Dr Shahriyari was my student for many years and he had good cooperation with the Atomic Energy Organization."
Iran's English language Press TV showed police and plain clothes security agents examining a silver-colored Peugeot 206 car with what looked like shrapnel holes in its bonnet.
No group has claimed the responsibility but Iranian officials and media both blamed Israel, which Teheran calls "the Zionist regime", and the United States for the killing of the nuclear scientist.
(中国日报网英语点津 Helen 编辑)
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Lee Hannon is Chief Editor at China Daily with 15-years experience in print and broadcast journalism. Born in England, Lee has traveled extensively around the world as a journalist including four years as a senior editor in Los Angeles. He now lives in Beijing and is happy to move to China and join the China Daily team.