Members of PJAK, the Party of Free Life of Kurdistan, raided a police station in Targovar near Orumieh city and killed four policemen including, three officers, Sarmayeh newspaper said.

It said the raid took place on Saturday night in Targovar, which is close to the Iraqi and Turkish borders in northwestern Iran.

In April, 18 policemen and eight rebels were killed in fierce gunbattle in Kermanshah province. Iran hit back promptly with helicopter attacks on three Iraqi Kurdish villages in a cross-border raid.

Western Iran, which has a sizeable Kurdish population, has seen deadly fighting in recent years between Iranian security forces and PJAK rebels operating out of rear-bases in neighbouring Iraq.

The group is closely allied with the Turkish Kurdish rebel group, the Kurdistan Workers' Party (PKK).

Iraq, Iran, Syria and Turkey all have significant ethnic Kurdish minorities.