DIYARBAKIR, Turkey, May 11 (Reuters) - Five mortar shells fell on Turkish soil on Monday after soldiers, thought to be Iranian, opened fire on Kurdish rebel positions in a remote area of northern Iraq, Turkish local officials said.

Kurdish separatist guerrillas based in remote mountainous areas in Iraq close to the borders with Turkey and Iran have long been a source of regional instability.

Security sources said it appeared the shells came from Iran.

Baghdad has condemned Iranian shelling of villages in Iraq's northern Kurdistan region. On Monday Iran urged Iraq to "pay special attention" to armed groups operating in its border.

"We received the information that five shells fell on the Turkish side of the border," an official at the governor's office in the province of Hakkari told Reuters.

Iran, whose forces often clash with guerrillas in its Kurdish-populated areas close to the Iraqi border, has neither confirmed nor denied reports its forces have shelled targets inside Iraqi territory.

Kurdish separatist guerrillas such as the the Party of Free Life of Kurdistan (PJAK) and the Kurdistan Workers' Party (PKK) are present in northern Iraq.

PJAK is an offshoot of the PKK, which took up arms in 1984 for an ethnic homeland in southeast Turkey. Iran, which like Turkey has a large Kurdish minority, sees PJAK as a terrorist group. The group seeks more autonomy for Kurds in Iran.

Turkey's military also conducts frequent air operations against PKK rebels in northern Iraq, but cooperation between Ankara and Baghdad has improved dramatically in recent months. (Writing by Ibon Villelabeitia; Editing by Louise Ireland)

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