An engineer died and another employee was injured after unexplained incident struck a major Iranian military and weapons development base east of Tehran, the country's state TV reported on Thursday.

Iran's Defense Ministry said the "accident" occurred on Wednesday afternoon at a research center at the Parchin military complex. It did not elaborate on the cause of the accident or provide any further details, but said that an investigation was underway. It identified the engineer who died as Ehsun Ghadbeigi.

Parchin is home to a military base where the International Atomic Energy Agency (IAEA) previously said it suspected Iran conducted tests of explosive triggers that could be used in nuclear weapons. Iran long has denied seeking nuclear weapons, though the IAEA previously said Iran had done work in "support of a possible military dimension to its nuclear program" that largely halted in late 2003.

Western concerns over the Iranian atomic program led to sanctions and eventually to Tehran’s 2015 nuclear deal with world powers. The U.S. under President Donald Trump unilaterally withdrew from the accord in May 2018, leading to a series of escalating attacks between Iran and the U.S. and Tehran abandoning the deal’s production limits. Tehran enriches uranium up to 60% purity – its highest level ever and a short technical step from weapons-grade levels of 90%

In 2015, the IAEA's then-director-general visited one suspected weapons-program site at Parchin and inspectors took samples there for analysis.

Iran’s missile and space programs have suffered a series of mysterious explosions in recent years. A giant unexplained blast struck in the area of Parchin in the summer of 2020, rattling the capital and sending a massive fireball into the sky near Tehran.