An explosion rocked the western Iranian city of Isfahan on Monday, resonating in several parts of the city, the semi-official Fars news agency reported. It is not clear what caused the blast, which has not been officially confirmed by the authorities.

A large uranium conversion plant, located some five kilometers from the center of Isfahan, processes uranium chemically to adapt it to the enrichment process with centrifuges carried out in other sites like Natanz.

According to reports, frightened residents called the fire department after the blast, forcing the city authorities to admit there had been an explosion.

Speaking with Fars news agency, Isfahan's deputy mayor confirmed the reports and said the authorities are investigating the matter. However, after the incident was reported by world media, the report was taken off the Fars website.

Isfahan authorities and the Iranian government released conflicting versions of the alleged explosion. One example is a statement given by the same deputy mayor to the Mehr news agency, saying he had no reports of an explosion.

ISNA, the Iranian Students' News Agency, cited a senior city official saying a "blast-like noise" had been heard in the city. Meanwhile, the Mehr news agency reported there had been a blast at a petrol station near the city. Another report pointed to a training accident.

The reported incident occurred about two weeks after General Hasan Tehrani Moghaddam was killed together with 20 other Revolutionary Guard members on November 12 at a military site outside Bidganeh village, 40 kilometers southwest of Tehran. The Revolutionary Guard said the accidental explosion occurred while military personnel were transporting munitions.

Satellite pictures of the damage caused by the explosion in Bidganeh were published on Monday, showing destroyed buildings.

Earlier on Monday, the head of the IDF Military Intelligence research section Brigadier General Itai Brun spoke about the mysterious explosion of two weeks ago for the first time. "The blast where the Iranians were manufacturing surface-to-surface missiles could delay or halt the development at the site," he told the Knesset's Foreign Affairs and Defense Committee.

He added, however, that Iran's nuclear program was continuing to gain ground, despite considerable international pressure and attempts to destabilize the Iranian regime.