Turkey has sent groundtroops into Iraqi Kurdistan to fight PKK rebels, who have bases in the region.
"Turkish security forces crossed the Iraqi border as part of the hot pursuit of PKK terrorists who were involved in the most recent attacks," a government source told AFP news agency.
"This is a short-term measure intended to prevent the terrorists' escape."
Air strikes on PKK bases were also launched on Tuesday, in further escalation of the violence.
A ceasefire between Turkey and the PKK collapsed in July as tensions in the region deepened after the advance of Islamic State militants and the strengthening Kurdish resistance to it, including by fighters linked to the PKK.
Turkey launched several air strikes on Kurdish bases with the PKK retaliating with attacks on security forces. Only on Tuesday 14 police officers died in a bomb blast blamed on the PKK.