"While the majority of the land and air operations are in (Turkey), mainly in the Cukurca region, ground and air strikes are ongoing in a few points in northern Iraq across the border," it said.

The Turkish army on Thursday initiated "a large-scale land operation" with 22 battalions against the Kurdistan Workers' Party (PKK) rebels, in five separate spots "inside and across the border."

The ground incursion is supported with air strikes, it said on its website.

The operations against rebels came after a string of coordinated PKK attacks early Wednesday in the towns of Cukurca and Yuksekova in southern Hakkari province near the Iraqi border, killing 24 soldiers and injuring 18.

The death toll is the worst for the army since 1993, when the PKK killed 33 unarmed soldiers in Bitlis province.

Clashes between the PKK and the army have escalated since the summer.

The PKK, listed as a terrorist organisation by Turkey and much of the international community, took up arms in Kurdish-majority southeastern Turkey in 1984, sparking a conflict that has claimed some 45,000 lives.