Turkey has operated several dozen military posts in northern Iraq for the past 25 years in its decades-old war against the Kurdistan Workers' Party (PKK), a group blacklisted by Turkey and many of its Western allies as a terrorist organisation.

Turkish President Recep Tayyip Erdogan on Saturday called for retaliation against the forces in northern Iraq and Syria.

"The blood of our soldiers has not been wasted, the separatist villains will be made to account for the blood they have shed," he said.

"We will continue with a vengeance to implement our strategy to eliminate terrorism at its source until the last terrorist is eliminated."

Ankara initially announced the deaths of six soldiers on Saturday, who "fell martyred in a clash with terrorists".

Ankara later announced six other soldiers were killed in northern Iraq in an earlier attack Friday night, which it attributed to the PKK.

A retaliatory military operation including "airstrikes" were being carried out in the region, authorities said.

According to Turkish media reports, Friday and Saturday's attacks occurred near Hakurk and Zap.

In October, Erdogan vowed to continue stepping up its strikes on "terrorist" targets in Iraq and Syria.