TEHRAN - An Iranian official accused the United States on Friday of involvement in a mosque bombing that killed more than 20 people in volatile south-eastern Iran, two weeks before the Islamic Republic's presidential election.

Jalal Sayyah, of the governor's office in Sistan-Baluchestan province, said three people had been arrested in connection with Thursday's blast in a crowded Shi'ite mosque in the city of Zahedan, in a region where many of Iran's minority Sunnis live.

The explosion, which some officials and media suggested was a suicide bombing, took place on a religious holiday in the mainly Shi'ite Muslim country. More than 80 people were wounded.

Iran has previously accused the United States, its arch-foe, of backing Sunni rebels operating on its border with Pakistan, who Tehran says are linked to the Islamist al Qaeda network.

The terrorists, who were equipped by America in one of our neighboring countries, carried out this criminal act in their efforts to create religious conflict and fear and to influence the presidential election, Sayyah told state radio.

He said two children were among the dead. The official IRNA news agency put the death toll at 25, naming all but one of the victims, who were men. Other media cited somewhat lower figures.

The person who detonated the device was standing among men praying in Ali Ebne-Abitaleb mosque and was also killed, provincial judiciary official Ebrahim Hamidi said.

It was one of the deadliest such bombing incidents in Iran since its 1980-88 war with Iraq. A blast in a mosque in the southern city of Shiraz killed 14 people in April last year but the country has been relatively peaceful in a turbulent region.

It has been confirmed that those behind the terrorist act in Zahedan were hired by America and the arrogance's other hands, Sayyah told the semi-official Fars News Agency.

Iranian leaders, who often accuse the United States and its allies of seeking to destabilize it, refer to Washington as the Great Satan guilty of global arrogance.

BLOOD-STAINED MOSQUE

Sistan-Baluchestan province, home to Iran's mostly Sunni ethnic Baluchis, is the scene of frequent clashes between security forces and heavily armed drug smugglers and bandits.

A senior cleric blamed Sunni extremists for the bombing but also suggested foreign enemies were involved in a bid to sow discord and conflict between Iran's Shi'ites and Sunnis.

The fingertips of America and Israel are definitely on this incident, Ahmad Khatami told Friday prayer worshippers in Tehran. The guilty would be arrested and severely punished.

Provincial governor Ali Mohammad Azad said the terrorist team behind the attack were being interrogated.

Defense analyst Paul Beaver said it was highly unlikely that the U.S. administration of President Barack Obama, who is seeking to engage Tehran diplomatically after three decades of mutual mistrust, would support Sunni insurgents in Iran.

He said history had shown that backing guerrilla groups to effect regime change was ineffectual and wrong, and the present U.S. administration does not want to be tarnished in that way.

In April, Iran's intelligence minister said it had arrested a group of people linked to Israel who were planning bombings ahead of the June 12 election, in which hardline President Mahmoud Ahmadinejad is seeking a second four-year term.

Presidential hopefuls including moderate former Prime Minister Mirhossein Mousavi condemned the incident.

Iranian media said a big part of the mosque was destroyed by the blast, which took place when many people were inside. Footage showed a blood-stained floor inside.

A bomb attack in Zahedan in early 2007 which killed 18 Revolutionary Guards was claimed by Jundollah (God's Soldiers), an insurgent group that says it is fighting for the rights of Iran's Sunni minority but which Tehran says is part of al Qaeda.

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