Turkey has been bombing sites in northeast Syria since Thursday, hitting civilian and military targets and infrastructure and causing casualties, according to Kurdish authorities.

"We have already intensified air operations and we will continue, and show the terrorists that we can destroy them anywhere and at any moment," Recep Tayyip Erdogan said, referring to fighters of the Kurdistan Workers' Party (PKK) -- listed as a terror group by Ankara and its Western allies.

Ankara has said that it launched a new wave of air strikes in retaliation for an attack in Ankara earlier this month that wounded two security personnel.

PKK has claimed responsibility for the attack, the first bombing to hit the Turkish capital since 2016.