Iran's intelligence minister said on Wednesday those behind a bomb blast in a mosque that killed 14 people last month also planned to target a Russian consulate in the Islamic state, an Iranian news agency reported.

President Mahmoud Ahmadinejad accused the United States, Israel and Britain on Tuesday of being responsible for the blast in the southern city of Shiraz that also wounded 200 people.

Iranian officials had previously said the April 12 explosion during an evening prayer sermon by a prominent local cleric, was caused by explosives left over from an exhibition commemorating the 1980-88 Iran-Iraq war.

Intelligence Minister Gholamhossein Mohseni-Ejei said 15 people had been arrested in connection with the incident and they were all Iranians, the semi-official Fars News Agency said.

"Those behind this incident were (also) trying to cause a bomb explosion in one of Russia's consulate-generals," he told Fars, without giving further details. The Russian embassy in Tehran was not immediately available for comment.

His ministry last week said it had arrested five or six members of a terrorist group with links to Britain and the United States, who it said were involved in the explosion.

Iran has yet to make public evidence against those arrested and the alleged involvement of the United States and Britain.

Tehran has in the past accused Washington and London of trying to destabilise the Islamic Republic by supporting rebels, mainly those in sensitive border areas.

Iran and the United States are at loggerheads over Tehran's nuclear programme, which Washington suspects is aimed at making bombs but which Tehran says is for producing electricity.

Security is normally tight in Shi'ite Muslim Iran and bomb attacks have been rare in recent years. Several people were killed in 2005 and 2006 in blasts in a southwestern province with a large Sunni Arab population