Turkey launched air operations "against terrorist targets in the north of Syria and Iraq", its defense ministry said Saturday, after 12 of its soldiers were killed over two days.

In a press release on its website, the ministry said "29 targets, including caves, bunkers, shelters, oil installations, and warehouses, were destroyed" during the operation carried out at 10:00 p.m. (1900 GMT).

An AFP correspondent as well as the Syrian Observatory for Human Rights reported strikes on Saturday evening against two oil sites in northeast Syria, near the Turkish border, without reporting any victims.

Two separate attacks on Turkish bases in northern Iraq killed a dozen of its soldiers.

Ankara has operated several dozen military posts in the area 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 organization.

Turkish President Recep Tayyip Erdogan on Saturday called for retaliation against "terrorists" 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".

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

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.

The PKK claimed responsibility for a suicide attack on October 1 that injured two police officers in Ankara.