The Revolutionary Guards killed in the attack were buried on Sunday

Revolutionary Guards members killed in Sunday's suicide bombing in south-eastern Iran have been buried.

Thousands of mourners, many in military uniforms, attended the funerals.

The attack in the province of Sistan-Baluchistan killed 42 people. It targeted the Revolutionary Guard, killing 15 of its members.

Iran has blamed Jundullah, a Sunni militant group. It has also accused the United States, Britain and Pakistan of some role in the attack.

All have denied any involvement.

Sunday's suicide bombing hit as Revolutionary Guards met tribal leaders in the Pishin district close to the Pakistani border.

SISTAN-BALUCHISTAN ATTACKS May 2009 A bomb explodes at a mosque in the provincial capital Zahedan, killing 19 and injuring 60. February 2007 Suspected militants killed 11, including Iranian Revolutionary Guards, in a bomb attack in the provincial capital Zahedan. March 2006 Gunmen posing as police kill 22 people, many government employees, after closing the Zabol-Zahedan road.

Profile: Iran's Jundullah militants Profile: Iran's Revolutionary Guards

The deputy commander of the Guards' ground force, General Noor Ali Shooshtari, and the Guards' chief provincial commander, Rajab Ali Mohammadzadeh, were among the dead.

Dozens of people were injured.

"The martyrdom of commander Shooshtari added a black page to the US and Israeli terrorist file," armed forces chief Maj Gen Hassan Firouzabadi said in a message read out at the ceremony, the official IRNA news agency reported.

'US action'

Iranian authorities summoned a senior Pakistani diplomat in Tehran, claiming that the assailants had arrived in Iran from Pakistan.

Parliament Speaker Ali Larijani has also said "US action" contributed to the attack.

Sistan-Baluchistan is mainly made up of the Baluchi ethnic group, who belong to the Sunni Muslim minority of Shia-ruled Iran.

Jundallah has previously been accused by Iran of terrorist activities in the province.

The region borders both Pakistan and Afghanistan, and has long been affected by smuggling, drug-trafficking, banditry and kidnapping.

Jundallah, also known as the Popular Resistance Movement of Iran, says it is fighting against the political and religious oppression of the country's minority Sunni Muslims.