ANKARA - Iran's foreign ministry has summoned Pakistan's ambassador in Tehran to protest against the killing of nine Iranian border guards by Sunni militants attacking from neighboring Pakistan, Iran's state news agency IRNA reported on Friday.The Sunni Muslim militant group called Jaish al Adl, or the Army of Justice, has claimed responsibility for the attack on Wednesday in Iran's Sistan-Baluchestan Province."Iran expects Pakistan to take serious and essential measures to arrest and punish those terrorists responsible for the killing of our nine guards," IRNA quoted Foreign Ministry spokesman Bahram Qasemi as saying."The message was delivered to Ambassador Asif Ali Khan Durrani on Friday," he said.Iran's southeastern Sistan-Baluchestan province, whose majority population is Sunni Muslim Baluch people like those across the border in Pakistan's Baluchistan province, lies on a major transit route for drug smugglers. It has long been plagued by unrest both from them and from separatist militants.Iranian President Hassan Rouhani also called on Pakistani Prime Minister Nawaz Sharif to prosecute the militants who had killed the Iranian border guards."Regrettably, a lack of appropriate measures and necessary prosecution on the part of the Pakistani government have caused great loss of lives and property for Iran," Rouhani said in a statement, quoted by the semi-official Mehr news agency.The Jaish al Adl group has in the past carried out several attacks against Iranian security forces, aimed at highlighting what they say is discrimination against Sunni Muslims and the ethnic Baluch in Shi'ite-dominated Iran. Iran denies the claim.The group killed eight border guards in 2015 and 14 border guards two years earlier.