TEHRAN, Iran — Two people were killed in an explosion at a defense ministry plant east of Tehran for the production of explosives, Iran’s state news agency IRNA reported Monday.

The Defense Industries Organisation, quoted by IRNA, said the fire broke out at the plant on Sunday night but it gave no further details.

The BBC, citing a report from the semi-official Iranian Students News Agency (ISNA), reported on Monday that the incident happened in an “explosive materials production unit” at the site south-east of the capital Tehran.

According to ISNA the blast was so powerful it shattered windows up to 12 kilometers away and the glare from the explosion lit up the night sky.

Several arms facilities and military bases are located east of the Iranian capital, including Parchin. UN nuclear inspectors have been seeking to visit the site to answer concerns about Iran’s atomic program.

The base lies at the centre of allegations of past Iranian research into sophisticated explosives that can be used to detonate a nuclear warhead.

Tehran, which has denied inspectors access to Parchin since 2005, insists its nuclear program is for purely civilian uses. Israel and the West fear Iran is seeking to attain nuclear weapons.

In August Iran reiterated that it will not allow IAEA inspectors to visit the site.

Nuclear experts from the IAEA were due to hold talks Tuesday in Tehran to try and resolve outstanding issues regarding Iran’s disputed atomic program.

The IRNA news agency said the visitors were expected in the capital on Monday night ahead of talks with Iranian officials.

IAEA inspectors have been given access to a string of declared nuclear sites as part of an interim nuclear deal reached with the major powers last November. Access to Parchin was not agreed under the terms of that accord but the IAEA has been seeking to visit the base as part of its mission to answer all concerns about Iran’s nuclear program, past and present.