The foreign office spokesman, Abdul Basit, also dismissed Iranian claims that Jundullah′s leader was in Pakistan.

′Crushing′ response

According to state media, one or more suicide bombers targeted the group of Revolutionary Guard leaders who had arranged to meet tribal leaders in the Pishin district close to the Pakistani border.

Reports said a suicide bomber detonated a belt packed with explosives as the meeting was about to start.

The deputy commander of the Guards′ ground force, General Noor Ali Shooshtari, and the Guards′ chief provincial commander, Rajab Ali Mohammadzadeh, were among at least six officers reported to have been killed.

Dozens of people were injured.

A top Guards officer has also vowed to deliver a "crushing" response to those behind the attack, according to Agence-France Presse.

Mr Ahmadinejad pointed towards Pakistan.

"We were informed that some security agents in Pakistan are co-operating with the main elements of this terrorist incident," he was quoted as saying by the semi-official Fars news agency.

"We regard it as our right to demand these criminals from them," he said, without elaborating.

"We ask the Pakistani government not to delay any longer in the apprehension of the main elements in this terrorist attack."

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

The Iranian foreign ministry also "protested against the use of Pakistani territory by the terrorists and rebels against the Islamic Republic of Iran," the Isna news agency reported.

Earlier, Parliament Speaker Ali Larijani said "US action" contributed to the attack - an accusation dismissed by the US.

Banditry and kidnapping

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 province 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 Sunni minority.

Local media cited officials as saying Jundallah had accepted responsibility for Sunday′s bombing, though there was no direct claim from the group.

ANALYSIS
Jon Leyne, BBC Tehran correspondent Jundallah, or Army of God, has been involved in a long-running insurgency in Sistan-Baluchistan.

Some experts believe they may have ties with the Taliban or al-Qaeda, operating in Pakistan and Afghanistan. That is disputed, and another possibility is that Jundallah maintains more informal links with ethnic Baluchis in the neighbouring countries.

Jundallah is also believed to have ties with drugs smugglers, who race across the border in heavily armed convoys, taking drugs on the lucrative smuggling route from Afghanistan through to Western Europe.