Updated

A top Iranian official accused the U.S. of hiring the bombers who carried out a devastating attack on a Shiite mosque in the southeastern city of Zahedan, killing as many as 23, Fars news agency reported on Friday.

"Three people involved with the terrorist incident were arrested," Jalal Sayah, a deputy provincial governor told the agency. "According to the information obtained they were hired by America and the agents of the arrogance."

Ali Mohammad Azad, the governor general of the province, told the official IRNA news agency 23 people were killed and 125 others were wounded in the attack, which was carried out during evening prayers.

The bombing was the deadliest such incident in the Islamic Republic in more than a decade, according to Reuters.

The blast, which may been a homicide bombing, went off in Zahedan, the capital of a lawless province that frequently witnesses clashes between police and gangs involved in drug smuggling. It has also seen attacks by an Islamic militant group called Jundallah, which claims to be fighting for rights of Sunni Muslims in mainly Shiite Iran but is suspected of Al Qaeda links.

Alaeddin Mazari, a local journalist in Zahedan, told The Associated Press that the explosion occurred in the second biggest Shiite Muslim mosque in the city, some 1,000 miles southeast of the capital, Tehran.

Ali Mohammad Azad, the governor of Sistan-Baluchistan province where Zahedan is the capital, told the official Islamic Republic News Agency the explosion happened at 7:45 p.m. and said a terrorist was involved, but didn't provide further details. He told state television that he detained some suspects who planned additional attacks ahead of the June 12 presidential election.

The state news agency quoted an unnamed official as saying part of the mosque was destroyed and rescue teams were transferring the bodies of the dead and injured.

In 2007, Jundallah, or God's Brigade, killed 11 members of the country's elite Revolutionary Guards in Zahedan.

Sectarian violence has been rare in other parts of Iran, but not totally absent.

Iran hanged three men last month for their involvement in a bombing inside a packed Shiite mosque in April 2008 that killed 14 people in the southern city of Shiraz, about 550 miles south of Tehran.

The blast went off as the mosque's cleric was delivering a weekly speech denouncing the Bahai faith and Wahabiism — an austere brand of Sunni Islam practiced mostly in Saudi Arabia, according to local news reports. Such speeches are not unusual in Iranian mosques.

Iran's Revolutionary Court said the three were members of the Iran Royal Association, a little known monarchist group that wants to overthrow the country's ruling Islamic establishment. It said they had ties to the U.S.

Tehran has repeatedly accused the U.S. and Britain of backing militants and opposition groups. Both countries deny it.

The Associated Press contributed to this report.