Iran has long fought Kurdish separatist groups who say they are struggling for more rights for the minority [GETTY]

At least four police officers and a bystander have been killed after gunmen opened fire on a police patrol in Iran's Kurdish region, an Iranian news agency reported.

The attack took place on Thursday in Sanandaj, the capital of Iran's Kurdistan province some 500km west of Tehran, where authorities have been battling a separatist Kurdish movement for years.

"In this terrorist incident five were killed including four policemen and a pedestrian," Ebrahim Kazeminejad, the provincial deputy police chief, told the semiofficial Mehr news agency.

"The two gunmen were members of "counter revolutionary groups".

He said five other policemen and four civilians were wounded in the attack, one of them in serious condition.

"Efforts were under way to apprehend the gunmen," he said.

In September, a deadly bombing killed 12 and injured scores of civilians at a military parade in the Kurdish city of Mahabad.

Iranian forces later crossed into neighbouring Iraq and killed 30 Kurdish fighters in retaliation.

Iran has long fought Kurdish separatist groups who say they are struggling for more rights for the minority, which makes up seven per cent of Iran's 75 million people.

Source: Agencies