President Recep Tayyip Erdogan said Thursday that Turkish security forces had arrested a "senior executive" of the extremist ISIS group.
Erdogan said the commander was known as Abu Zeyd.
His real name was Bashar Khattab Ghazal al-Sumaidai, Erdogan told reporters on board his flight home from a three-nation tour of the Balkans, AFP reported.
Erdogan said a UN Security Council report published in July identified Sumaidai as "one of the senior executives of the (ISIS) terrorist organization".
Turkish media said there were some indications Sumaidai may in fact be the man known as Abu Hasan al-Hashimi al-Qurashi -- an Iraqi who is the new self-proclaimed caliph, or leader, of the entire ISIS group.
Erdogan only referred to Sumaidai as a top ISIS official in Syria.
"In his interrogation, he also stated that he was a so-called 'qadi' of the so-called ministry of education and ministry of justice," Turkish media quoted Erdogan as saying.
Erdogan did not say when the ISIS commander was captured.
"This terrorist's connections in Syria and Istanbul had been followed for a long time, and intelligence information was obtained that he would enter Türkiye illegally," Erdogan said.
"This terrorist was caught in a successful operation of the MIT security service and the Istanbul police."
After a meteoric rise in 2014 in Iraq and Syria that saw it conquer vast swathes of territory, ISIS saw its self-proclaimed "caliphate" collapse under a wave of offensives.
It was defeated in Iraq in 2017 and in Syria two years later, but sleeper cells of the extremist group still carry out attacks in both countries.
Syria's war began in 2011 and has killed nearly half a million people and forced around half of the country's pre-war population from their homes.