An aerial image from 2004 the Parchin military complex, near Tehran, Iran. Image: isis-online.org.

An explosion at an Iranian gas storage facility close to a sensitive military site near the capital Tehran was caused by a tank leak, a Defense Ministry spokesman told state TV on Friday.

The explosion took place in the “public area” of Parchin, said the spokesman, Davoud Abdi, as opposed to the military site, where Western security services believe Tehran carried out tests relevant to nuclear bomb detonations more than a decade ago.

Abdi said the fire was brought under control and there were no casualties because the incident happened in a hilly non-residential area.

Videos and pictures posted on social media that were picked up by local news outlets showed an explosion with a bright orange flash, followed by a large plume of smoke.