Germany will support Ankara in its fight against extremists, Chancellor Angela Merkel told Turkish Prime Minister Ahmet Davutoğlu in a phone call on Sunday, but she also urged the Nato partner to keep measures appropriate.

Davutoglu informed Merkel by phone about the actions of the Turkish government in the "fight against terrorism" following the attacks in Suruç and other attacks against Turkish security forces, a German government spokesman said.

Merkel assured Davutoğlu of Germany's solidarity and support, the spokesman said, but he also added: "In this context she recalled the principle of proportionality in the implementation of necessary measures.

"The Chancellor also appealed that the peace process with the Kurds should not be given up, but continued despite all the difficulties," the spokesman added.

Turkey has stepped up efforts against terrorism following a suspected ISIS bomb attack carried out on Monday in the country's southeastern Şanlıurfa province which killed 32 people and injured dozens.

Two policemen were killed in retaliation on Wednesday, for which the outlawed PKK organization claimed responsibility.

On Thursday, gunfire from Syria killed a Turkish military officer and injured two troops in southern Kilis province, prompting Turkish forces to return fire.

Since then, Turkey has initiated a nationwide anti-terror operation, detaining many suspected of having ties with the self-proclaimed Islamic State of Iraq and al-Sham (ISIS) as well as the outlawed PKK organization.

Turkish Air Forces has been also carrying airstrikes against the PKK in northern Iraq and the ISIS militants in northern Syria.