An Iranian nuclear scientist has reportedly been assassinated in Tehran.
The Isna news agency says Daryoush Rezaei, 35, was shot dead outside his home. It also says his wife was wounded.
Isna said that Mr Rezaei was an expert with links to the Atomic Energy Organisation of Iran.
In 2010, nuclear scientist Massoud Ali Mohammadi was killed by a remote-controlled bomb in Tehran.
Iran blamed that attack on Mossad, the Israeli secret service.
The BBC reports the United States, Israel and many Western nations oppose Iran's atomic programme, believing it to be a front to create a nuclear bomb.
Iran insists its nuclear programme is for purely peaceful purposes.
Earlier this week, Iran said it was installing newer and faster centrifuges at its nuclear plants, with the goal of speeding up its uranium enrichment process.
Enriched uranium can be used for civilian nuclear purposes, but also to build atomic bombs.