Tehran: Iran's Intelligence Ministry said on Saturday US agents had armed and trained those behind a deadly blast in a mosque last month and that pipelines in the country's oil-rich south were also among the planned targets.

President Mahmoud Ahmadinejad said on Tuesday Iran had evidence the United States, Britain and Israel were involved in the April 12 blast in the southern city of Shiraz that killed 14 people and wounded 200.

Iranian officials had initially said the explosion during an evening prayer sermon was caused by explosives left over from an exhibition commemorating the 1980-88 Iran-Iraq war.

The Islamic Republic, which is embroiled in a standoff with the West over Tehran's disputed nuclear plans, has yet to make public evidence against those arrested and the alleged involvement of its old foes.

Iran's allegations about the Shiraz explosions are similar to accusations US officials have made about Iranian support for militias in Iraq that have fought US and US-backed government forces there, charges Tehran denies.

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

List of suspected targets

Intelligence Minister Gulam Hussain Mohseni Ejei said on Wednesday 15 Iranians had been arrested in connection with the blast and they had also plotted to attack a Russian consulate in northern Iran.

His ministry issued a new statement yesterday, saying one of those behind the bombing was killed in an arrest operation.

It also added to the list of the group's suspected targets to include oil pipelines, a book fair in the capital Tehran as well as scientific, religious and educational facilities.

"This network that the Americans had armed with different terrorist tools such as chemicals, explosive materials, dangerous and poisonous cyanide ... was guided directly by American agents into Iran," it said in a statement carried by the official Irna news agency.

It said confessions of those arrested "show that American agents had told members of this network that their main mission was to spread fear among people in different cities".

Blowing up southern oil pipelines was among the group's targets and this was why American centres had set up diving classes for this network to identify oil pipelines in the Gulf, the statement said.

Weapons, explosives and maps were among items seized from those arrested, the Intelligence Ministry said.