Two workers are dead after a fire and explosion at a military explosives facility that’s part of Iran’s Parchin nuclear complex, reports say.

The fire occurred in an "explosive materials production unit" Sunday, the BBC reported Monday, citing the semi-official Iranian Students News Agency (ISNA).

A pro-opposition website reported a large blast near the Parchin military site, southeast of Iran’s capital Tehran, but that has not yet been confirmed.

Parchin has been linked to Iran's controversial nuclear program. Iran has denied the International Atomic Energy Agency (IAEA) access to the complex since 2005.

Pro-reform  website Sahamnews said the explosion was so intense, it shattered windows of buildings as far as 9 miles away.

"Unfortunately, due to the incident, two workers of this production unit lost their lives," ISNA reported, quoting Iran's defense industries organization.

There were no further details.

The IAEA said in September that more activity had been conducted at the Parchin military base. It said Iran had also missed a deadline to answer further questions about its nuclear program.

Western countries suspected Iran of trying to develop a nuclear weapon but Iranian leaders insist they only want atomic energy. Iran claims Parchin is a conventional military facility and that its nuclear program is peaceful.

Iran is in negotiations with six world powers on a permanent agreement over its nuclear industry. Talks are focused on lifting Western sanctions in exchange for a scaling-back of Iran's uranium enrichment program. A deadline for the agreement has been set for November 24th.

Iran said a massive explosion at a military base 28 miles west of Tehran killed 17 Revolutionary Guards three years ago, including a leader of its elite force’s missile program. It said that the blast – which occurred while weapons were being moved-- was accidental, Reuters reported.