The Kurdistan Democratic Party of Iran (KDPI) has carried out sporadic attacks inside Iran from its rear-bases in Iraq and is blacklisted as a "terrorist" group by Tehran.

The leftist organisation was holding a meeting at the time of the attack, one of its officials told AFP on condition of anonymity.

He blamed the attack on Tehran.

"Eleven KDPI members were killed and 30 wounded by Katyusha rockets fired on their headquarters in Koysinjaq," Kamran Abbas, director of the city's hospital, told AFP.

Koysinjaq is about 60 kilometres (35 miles) east of the autonomous Kurdish region's capital Arbil.

Abbas said the party's secretary general and his predecessor were among the wounded.

The KDPI is Iran's oldest Kurdish movement and has seen several of its leaders assassinated by Tehran in the past.

Iranian security forces have also carried out repeated operations against KDPI bases in the mountainous terrain along the border.