A joint operation by Turkish anti-terrorism police and the national intelligence agency has seen at least 124 people detained, suspected of links to the so-called Islamic State group (IS).
Reports from a Turkish news outlet - the Anadolu Agency - indicate that house raids have been executed simultaneously throughout the country.
Homes in Ankara, the Turkish capital, and Istanbul were reportedly targeted by the police, with foreign nationals among those detained.
The Anadolu Agency says 33 of the suspects apprehended in Ankara were foreign nationals - including people from Iraq, Syria and Morocco.
In Istanbul, 31 houses were raided as police detained 24 suspects, including four foreign nationals.
Raids also took place in the cities of Batman, Adana, Kayseri, Samsun and Bursa.
Last month, Turkish President Recep Tayyip Erdogan threatened to release IS prisoners in response to EU-imposed sanctions.
He accused European nations of not taking responsibility for their nationals, adding that Turkey was "not a hotel" for foreign fighters.
Relations between Turkey and other NATO nations have been strained since a controversial cross-border offensive into Syria in October.
Interior Minister Suleyman Soylu says Turkey deported a total of 778 jihadists back to their home countries in 2019.
Cover image: Library image of Ankara skyline (Picture: PA).