Baghdad, May 17 : Three Yazidi militiamen affiliated with the Turkish Kurdistan Workers' Party (PKK) were killed and a fourth wounded in a Turkish airstrike in Iraq's northern province of Nineveh, the Counter-Terrorism Service of the semi-autonomous Kurdistan region said in a statement. Around midday local time (0900 GMT), a Turkish aircraft bombarded the headquarters of a Yazidi militia, known as the Sinjar Protection Units (YBS), near the town of Sinjar, nearly 120 km west of Nineveh's provincial capital Mosul, killing three militiamen and wounding another, the statement added on Tuesday. The YBS is a Yazidi militia formed in Iraq in 2007 to protect the Yazidi community in Iraq. The group has strong links to the PKK group, Xinhua news agency reported. PKK is listed as a "terrorist" group by Turkey, the US, and the European Union, and the Turkish forces frequently carry out ground operations, airstrikes, and artillery bombardments against its positions in northern Iraq, especially the Qandil Mountains, the main base of the PKK. /IANS