Iran's Foreign Minister Mohammad Javad Zarif on Friday slammed Turkish President Recep Tayyip Erdogan for an "ill-recited" poem, seen as implying Iran's northwestern provinces were part of Azerbaijan.

European Union leaders early Friday gave the green light for the expansion of sanctions against Turkey over its exploration of gas reserves in Mediterranean waters claimed by EU members Greece and Cyprus.

"Regrettably, Turkey has engaged in unilateral actions and provocations and escalated its rhetoric against the EU, EU member states and European leaders," they said in a statement from their summit in Brussels.

Turkish police on Tuesday detained 198 people, including soldiers, in nationwide raids over alleged ties to the group blamed for a 2016 coup attempt, state news agency Anadolu reported.

Turkish President Recep Tayyip Erdogan believes "a win-win formula" can be found in a row with Greece over undersea resources, according to comments published on Monday, as EU leaders mull sanctions ahead of a summit.

European Council chief Charles Michel said Friday that Turkey has not de-escalated its stand-off with Greece in response to diplomatic outreach and warned EU member states would now consider sanctions.

A Turkish soldier was killed in Turkish-controlled northern Syria on Thursday during clashes with Kurdish militia forces deemed "terrorists" by Ankara, the defence ministry tweeted. 

With sloppy restoration work and damaged or disfigured historical monuments, experts say a race for profits, ideological considerations and favouritism are leaving sensitive upkeep of cultural heritage by the wayside in Turkey.

A Turkish research ship at the centre of a row with Greece over potential gas riches in the eastern Mediterranean has returned to port, Turkey's energy ministry said Monday.

A Turkish court jailed 337 former pilots and other suspects for life in one of the largest trials stemming from the bloody 2016 coup attempt against President Recep Tayyip Erdogan.

Clashes between Kurdish fighters and Turkey-backed opposition gunmen in northern Syria left at least 11 fighters dead in some of the most intense fighting in weeks between the two sides, an opposition war monitor and a Kurdish spokesman said Tuesday.

Exchange of fire and shelling between the Kurdish-led Syrian Democratic Forces and Turkey-backed opposition gunmen who identify as the Syrian National Army have not been uncommon since Turkish troops invaded parts of northern Syria in October of last year.