Rostam Joudi, a member of the Pejak party, told AFP that Iranian forces fired shells across the border towards his group's positions in four villages near the towns of Rania and Kalaat Diza in the Iraqi province of Sulaimaniyah.

It was not clear whether there were any casualties in the barrage, which lasted for around an hour, he added.

Iranian artillery last targeted Iraq-based Pejak forces in March and April of this year, killing four people on the countries' mountainous frontier.

According to Tehran, Pejak is allied to the Kurdistan Workers' Party (PKK), a militant separatist group which since the early 1980s has been fighting for the independence of Turkey's Kurdish minority.

The Kurds' traditional homeland stretches across portions of southeast Turkey, northern Syria, Iraq and Iran. Turkey and Iran accuse Kurds based in Iraq of carrying out cross-border attacks.