Six senior Revolutionary Guards commanders were among those killed in Sunday's attack in Iran's southeastern province of Sistan-Baluchestan, state television reported.

A suicide bomber killed around 20 people, including the senior Revolutionary Guards commanders, Iranian media reported.

Another 40 people were wounded in the most severe attack on the Revolutionary Guards in recent years.

State television suggested that a Sunni rebel group called Jundollah (God's soldiers) -- linked by some analysts to the Taliban in neighbouring Pakistan -- was the likely suspect for the attack.

'Attacker detonated explosives strapped to his body during gathering of tribal heads,' state Press TV said in a headline, adding that civilians and tribal leaders were also among the victims.

The Revolutionary Guards blamed 'foreign elements' linked to the United States for the killings, which underlined deepening instability in Iran's southeast bordering Pakistan and Afghanistan.

Tehran accuses the United States of backing Jundollah to create instability in the country but Washington denies this.

State broadcaster IRIB said the attack occurred in the morning at the gates of a conference hall in the city of Sarbaz in Sistan-Baluchestan. The province is the scene of frequent clashes between security forces, Sunni rebels and drug traffickers.

The two high-ranking commanders were the deputy head of the Guards' ground forces, General Nourali Shoushtari, and the Guards' commander in Sistan-Baluchestan province, General Mohammadzadeh, news agencies reported. Shoushtari was also a senior official of the Guard's elite Qods force, media said.

State TV said several senior officers were killed, but did not give additional names. Citing authorities and experts, a presenter of English-language Press TV said 'the finger of accusation is directly pointed at the Jundollah group,' referring to ethnic Baluch Sunni insurgents who have been blamed for previous attacks in the region.

The Revolutionary Guards pointed the finger at US
involvement. 'Surely foreign elements, particularly those linked to the global arrogance, were involved in this attack,' a Guards statement quoted by television said. Iran often uses the term 'global arrogance' to refer to the United States, its old foe.
   

The Revolutionary Guards is an elite force seen as fiercely loyal to the values of the 1979 Islamic revolution. It handles security in sensitive border areas.

Jundollah, which claimed responsibility for a bomb attack on a Shi'ite mosque in May that killed 25 people, says it is fighting for the rights of the Islamic Republic's minority Sunnis.

Some analysts believe that Jundollah has evolved through shifting alliances with various parties, including the Taliban and Pakistan's ISI intelligence service, who saw the group as a tool against Iran.

Predominantly Shi'ite Muslim Iran has also linked Jundollah to the Sunni Islamist al Qaeda network. Most people in Sistan-Baluchestan are Sunni Muslims and ethnic Baluchis. Iran rejects allegations by Western rights groups that it discriminates against ethnic and religious minorities. - Reuters