Tehran, July 17 - Iran's intelligence minister has warned worshippers against potential unrest during the address by the reformist cleric Ayatollah Ali Akbar Hashemi Rafsanjani Friday, media reports said Friday.

Rafsanjani, who has backed presidential contender Mir-Hossein Mousavi, could add fuel to the opposition protests, Gholamhossein Mohseni-Eje'i said Thursday, while calling on worshippers to remain 'vigilant so that the Friday prayers do not turn into a scene of undesirable events', Fars news agency reported.

The minister however said that security arrangements have been put in place in the capital to prevent any untoward incidents.

Rafsanjani, the chairman of Iran's Expediency Council, will lead the Friday prayers after weeks of absence since the disputed June 12 elections that saw incumbent President Mahmoud Ahmadinejad winning with over 62 percent of the votes.

His main challenger Mousavi received only 33 percent of votes, which he attributed to electoral fraud carried out by the interior ministry.

Supporters of Mausavi and other opposition leaders are believed to be planning to take part in the prayers en masse, as Mousavi has already announced his participation in Friday prayers, posing a threat of fresh violence in the country.