Feb. 14 (Bloomberg) -- Eleven employees of Iran's Revolutionary Guards died in a bombing in Sunni Muslim-dominated Sistan-Baluchistan province, where attacks on the Shiite Muslim- led central government have escalated in the past year.

Thirty-one other employees were hurt when the car bomb exploded early today in Zahedan near a bus belonging to Revolutionary Guard ground forces, a provincial official in the city, who declined to be identified, said in a telephone interview. The toll was revised after an initial report that 18 people died, the state-run Islamic Republic News Agency said.

Armed men on two motorcycles opened fire on the bus as it got near the car, parked along the road. The bomb was detonated as the bus slowed down, IRNA said.

``Five terrorists directly responsible for the Zahedan bombing have been arrested,'' IRNA cited Soltan-Ali Mir, political head at Sistan-Baluchistan's provincial office, as saying, without providing details of the suspects or the motive for the attack.

The ``main culprit'' was killed by security forces at the scene of the accident, Zahedan Governor Hassan-Ali Nouri was quoted as saying by IRNA in a separate report.

``A group known as `Jundallah' under the leadership of Abdolmalek Rigi, one of the insurgents from the east of the country, has issued a statement, taking responsibility for the terrorist move'' the state-run Fars news agency reported.

Jundallah, or ``the Army of God,'' is a militant Sunni group based in Pakistan and operating in Iran's southeastern border.

Nationalist Revolts

Nationalist revolts by Sunnis from the province's Baluchi ethnic group preceded the 1979 Islamic Revolution that toppled the country's monarchy, the United Nations High Commissioner for Refugees said in a 1997 report. The unrest has continued since the religious leadership appointed a Shiite member of the ethnic Sistan minority as the province's governor, the UNHCR said.

The Zahedan attack is the most deadly in the southeastern province since May, when officials said insurgents killed 12 civilians. Iranian forces responded, killing four militants. Insurgents killed 22 people driving between Zabol and Zahedan in March. In April, insurgents killed two army officers and injured a cleric in the province, officials said.

A group of Iranian soldiers was kidnapped in November 2005 and released two months later. In videotapes, the kidnappers identified themselves as members of Sunni militant group Jundallah.

The Revolutionary Guards are the members of the military most loyal to the Shiite clerics who control the government.

Zahedan is the capital of Sistan-Baluchistan province, which is bordered by Afghanistan and Pakistan to the east. It is a main entry point for opium and heroin coming from Afghanistan. A local official contacted in Zahedan declined to specify the size of the Sunni majority in the province, saying the information was sensitive. Iran's population is 89 percent Shiite Muslim.

To contact the reporters on this story: Ladane Nasseri in Tehran at lnasseri@bloomberg.net; Marc Wolfensberger in Tehran at mwolfens@bloomberg.net

Last Updated: February 14, 2007 07:53 EST