Eight executives of Turkish Medical Association, including its chairman were arrested in capital Ankara on Tuesday on terrorism charges.
Earlier, the Chief Public Prosecutor's Office in Ankara issued arrest warrants for 11 executives of the association.
An Ankara-based operation is currently underway in eight provinces to arrest the remaining members.
The arrests came after the Interior Ministry filed a complaint at the Chief Public Prosecutor's Office in Ankara.
The suspects have been accused of “legitimizing terror group’s activities”, “praising crime and criminals”, and “inciting hatred and enmity among people”.
On Saturday, Deputy Prime Minister Bekir Bozdag also slammed the association’s statement against Afrin operation, calling it, “shameful and unacceptable”.
Last week, the association in a statement had questioned the ongoing Operation Olive Branch in Syria's Afrin region.
On Jan. 20, Turkey launched Operation Olive Branch along with Free Syrian Army (FSA) to clear PYD/PKK and Daesh terrorists from Afrin, northwestern Syria.
As the operation entered its 11th day, the Turkish General Staff announced that at least 649 PYD/PKK and Daesh terrorists have been "neutralized" since the beginning the operation.
According to the Turkish General Staff, the operation aims to establish security and stability along Turkey’s borders and the region as well as to protect Syrians from oppression and cruelty of terrorists.
The operation is being carried out under the framework of Turkey's rights based on international law, UN Security Council resolutions, its self-defense rights under the UN charter, and respect for Syria's territorial integrity, it said.
The military also said only terror targets were being destroyed and that "utmost care and sensitivity" was being given to not harm any civilian.
Afrin has been a major hideout for the PYD/PKK since July 2012, when the Bashar al-Assad regime in Syria left the city to the terror group without putting up a fight.