Seven people were killed in an explosion at an Iranian steel mill that has been linked to the country's nuclear program.
The explosion occurred Dec. 11 at the Ghadir steelworks. The plant opened six months ago.
Some of the dead are believed to be North Korean nuclear experts, according to reports. The mill reportedly is processing North Korean steel in order to produce the proper grade of steel to construct centrifuges for uranium enrichment.
Iranian news reports said a gas leak caused the blast, but other reports indicated that the explosion may have been the result of sabotage.
The explosion comes weeks after two other unexplained explosions at sites linked to the Islamic Republic's nuclear program.