The suicide bomber who carried out last week's attack that killed 27 members of Iran's Revolutionary Guards was a Pakistani national, the elite force claimed on Tuesday.

“The suicide bomber was named Hafez Mohammad-Ali and was from Pakistan,” alleged Brigadier General Mohammad Pakpour, commander of the Guards' ground forces, quoted by the force's Sepah news agency.

The February 13 suicide bombing killed 27 Revolutionary Guards on a bus in the volatile southeastern province of Sistan-Baluchistan which borders Pakistan.

The general said the probe into the attack had made headway after the model of the explosives-packed car that exploded next to the bus had been identified.

“Two days ago the first clue, a woman, was identified and arrested, and through this woman, we reached others,” Pakpour said.

Apart from the suicide bomber, one of the suspected accomplices was also Pakistani, he said.

Pakpour said an attack had originally been planned for February 11 to coincide with celebrations for the 40th anniversary of Iran's Islamic revolution. But security forces had been “fully prepared” on that day, he said.

A militant group, Jaish al-Adl (Army of Justice), which Tehran says operates mostly out of bases in Pakistan, claimed responsibility for the attack.