Iranian media report that authorities have detained three people in connection with Sunday's suicide bombing that killed 42 people, including 15 members of Iran's elite Revolutionary Guards.
<!-- IMAGE -->Iran's Fars news agency Tuesday quoted a top Iranian prosecutor, Mohammad Marzieh, as saying that the three were apprehended in Sistan-Baluchestan, the province where the bombing occurred. He also said the suicide bomber has been identified as an Iranian national.
Media in Iran also quote Revolutionary Guards chief General Mohammad Ali Jafari as vowing to "retaliate" against U.S. and British intelligence agencies that he says helped the bombers.
He also accused Pakistani intelligence agents of links to Jundallah, the Sunni militant group that claimed responsibility for the blast.
The Pakistani, U.S. and British governments condemned the attack and denied any involvement.
Among those killed in the bombing were six Revolutionary Guards commanders.
Iranian media say President Mahmoud Ahmadinejad urged his Pakistani counterpart Asif Ali Zardari to help hunt down the bombers.
Mr. Ahmadinejad said the two neighbors have a "brotherly relationship." But, he also said the presence of what he calls "terrorist elements" in Pakistan is unjustifiable.
General Jafari said Iran is sending a delegation to Pakistan to demand that it hand over Jundallah's leader, Abdelmalek Rigi.
Rigi says his group is fighting discrimination against fellow ethnic Baluchis, who are members of Iran's Sunni minority.
The bomber in Sunday's attack blew himself up at a sports complex in the town of Pisheen, where the Revolutionary Guards were preparing to meet Shi'ite and Sunni tribal leaders.
Some information for this report was provided by AFP and Reuters.