Iran's elite Revolutionary Guards said Monday it has arrested three "terrorists" involved in last week's deadly suicide bomb attack on security forces in a region bordering Pakistan.
"Safe houses in (the cities of) Saravan and Khash were identified and eliminated, and the terrorists based in them were arrested," the force said on its official Sepah news agency.
"Three of the terrorists were arrested and 150 kilograms (330 pounds) of explosives and 600 kilograms of explosive materials as well as weapons and ammunition were confiscated," it said.
The Guards said the three arrested had "produced, guided and supported" the vehicle used in Wednesday's suicide bombing.
The attack killed 27 members of Iran's Revolutionary Guards travelling on a bus in the volatile southeastern province of Sistan-Baluchistan, which straddles the border with Pakistan.
It was claimed by the jihadist outfit Jaish al-Adl (Army of Justice).
Iran has provided Pakistani officials with "information on the terrorist groups' hidden and semi-hidden training centres", army chief-of-staff Mohammad Bagheri told Tasnim news agency.
In a phone call with Pakistani army commanders, Bagheri asked them to "either confront the groups or allow (Iranian) forces to enter."
Islamabad launched an operation against the "terrorists" in its Balochistan border province on Sunday, he said.
Guards commander Major General Mohammad Ali Jafari has accused Pakistan's army and intelligence agency of sheltering the jihadists.
The foreign ministry said Iran "cannot tolerate" Pakistan's inability to stop cross-border attacks on Iran and said Tehran's frustration had been communicated to Islamabad.
"We hope the Pakistani government can and wants to prevent such things from happening again," spokesman Bahram Ghasemi told reporters on Monday.
The ministry has summoned the Pakistani ambassador in Tehran and urged Islamabad to "seriously confront... the terrorist groups active on its border" with Iran.