The privately run Dogan news agency reported that 150 people were arrested in the southern province of Sanliurfa, which shares a border with Syria. Materials relating to so-called "Islamic State" (IS) militants were also found during the raids conducted at multiple properties.

Turkey's state-run Anadolu Agency said 60 suspects were apprehended in the capital, Ankara, adding that the majority of those were not Turkish nationals. Police operations were also carried out in the major cities of Istanbul, Izmir, Bursa and Kocaeli, as well as in the southern provinces of Adana, Diyarbakir, Hatay and Adiyaman. Other cities and provinces were also subject to raids, and weapons and ammunition were found at least during some of the operations.

'Children' among those arrested

Anadolu said at least some of the suspects had been charged with being members of an armed terrorist organization and mentioned in an earlier report that 10 "children" were among those taken into custody. The news agency later amended its information to say "minors" instead of "children." There was no detail given on the actual age of those arrested.

In addition to these latest arrests, at least 780 people, including 350 foreigners, remain in detention on related terrorism charges, according to official sources.

The Turkish government holds IS responsible for a number of attacks that have ravaged the country in the past two years; most recently, IS claimed responsibility for the New Year's Eve assault on the Reina nightclub in Istanbul in which 39 people were killed.

Turkey's 'war on terror'

In the wake of the July 15 coup attempt in Turkey, President Recep Tayyip Erdogan and his Justice and Development Party (AKP) have embarked on a multipronged clampdown on dissident groups as well as violent insurgents. Turkey accuses the US-based cleric Fethullah Gulen of being the mastermind behind the failed putsch; the Anadolu Agency said some of those arrested during the overnight raids might have links to the preacher.

In August 2016, the Turkish army started getting involved in the fight against IS in neighboring Syria as part of what the military refers to as "Operation Euphrates Shield."

As a member of NATO, Turkey's military involvement in Syria is considered to be part of the US-led coalition effort against IS in the north of Syria.

The Turkish offensive continued throughout the weekend, with heavy bombardments of targets in northern Syria reportedly "neutralizing" 33 IS fighters, according to Anadolu.

Turkey's offensive in Syria is increasingly fueling anti-Turkish sentiments among IS fighters, and all major cities across Turkey are on high alert about further potential suicide bombings.

ss/sms (AP, Reuters, dpa)