An anti-aircraft system destroyed one drone and two others exploded, the ministry said, adding there were no casualties and only minor damage to the site in the central province of Isfahan.

A fireball lit up the night sky in video footage widely shared on social media and published by Iranian state media, with people outside seen running and emergency service vehicles speeding toward the site.

"An unsuccessful attack was carried out ... on one of the workshop complexes of the ministry of defence," the ministry said, according to state news agency IRNA.

"The attack, which occurred around 11:30 pm (2000 GMT) on Saturday, did not cause any disruption to the operation of the complex," it said.

Authorities did not elaborate on the activities at the site, but IRNA said the strike had targeted "an ammunition manufacturing plant".

Parliament member Mohammad-Hassan Assafari told the Mehr news agency that "opponents and enemies" of Iran were aiming to "disrupt the defencive power" of the country with the attack.

The drone strike comes at a tense time in Iran, which has been rocked by protests over the death in custody of Kurdish-Iranian woman Mahsa Amini in September, and as the standoff with major powers over its nuclear programme remains unresolved.

Iran has also faced accusations by Western countries that it has been supplying armed drones to Russia for use in the war in Ukraine, a charge Tehran denies.

- Major blaze -

Iran has been engaged in a shadow war for years with its arch foe Israel, blamed for a series of sabotage attacks and assassinations targeting the Iranian nuclear programme, and with Israel's ally the United States.

A few hours before the Isfahan attack, a major fire broke out at a motor oil production plant in the northwestern province of East Azerbaijan, IRNA reported.

Images of the huge blaze in the key industrial complex of Shahid Salimi linked to the Ministry of Industry were published by the agency.

It said the fire was brought under control by firefighters, and authorities were investigating the cause of the blaze.

Shahid Salimi, located in the city of Azarshahr, is the largest industrial zone in northwestern Iran. It hosts 790 factories and other facilities employing nearly 28,000 workers, according to state media.

- Nuclear sites -

Iran has several known nuclear research sites in the Isfahan region, including a uranium conversion plant.

In April 2021, Tehran announced that it had started producing 60 percent enriched uranium at the Natanz site in Isfahan province.

Negotiations to revive the 2015 nuclear deal, known formally as the Joint Comprehensive Plan of Action, between Iran and world powers has stalled for months for multiple reasons, including the protests in the country.

The agreement offered Iran sanctions relief in exchange for curbs on its nuclear programme to guarantee that Tehran could not acquire or build a nuclear weapon -- an objective it has always denied pursuing.

But in 2018 then-US president Donald Trump declared a unilateral withdrawal from the accord and re-imposed a painful sanctions regime, which has since prompted Iran to begin rolling back on its own commitments.

Iran's nuclear programme has been the target of sabotage, targeted assassinations of scientists and several campaigns of cyber-attacks.

Iran has accused Israel of carrying out several covert actions on its soil, including an attack allegedly using a satellite-controlled machine gun which killed leading nuclear physicist Mohsen Fakhrizadeh in November 2020.