By Tuvan Gumrukcu and Dominic Evans

ANKARA (Reuters) – Turkey has so far detained 573 people for social media posts and protests criticizing its military offensive in Syria, the government said on Monday.

The crackdown, which has extended to the national medical association, has deepened concerns about free speech under President Tayyip Erdogan, who has criticized opponents of the military intervention as “traitors”.

Turkey last month launched an air and ground offensive, dubbed Operation Olive Branch, against the Kurdish YPG militia in Syria’s northwestern Afrin region. Authorities have repeatedly warned they would prosecute those opposing, criticizing or misrepresenting the incursion.

“Since the start of Operation Olive Branch, 449 people have been detained for spreading terrorist propaganda on social media and 124 people detained for taking part in protest action,” the Interior Ministry said in a statement.

The operation has been widely supported by Turkey’s mainly pro-government media and by most political parties, with the exception of the pro-Kurdish opposition.

Last week, a prosecutor ordered the detention of 11 senior members of the Turkish Medical Association, including its chairman, after the organization criticized the incursion, saying: “No to war, peace immediately”.

Erdogan criticized the body as traitors. All of the doctors have since been released on probation, the association said on Twitter. Detention orders have been issued for another 13 people for supporting the medics.

“There are laws that prohibit the glorification of terrorism, support for terrorism through propaganda and media. The prosecutors are implementing the laws,” Erdogan’s spokesman, Ibrahim Kalin, told reporters in Istanbul at the weekend.

Ankara considers the U.S.-backed YPG, which controls Afrin, to be a terrorist group and an extension of the Kurdistan Workers Party (PKK) which has fought an insurgency in Turkey’s largely Kurdish southeast since 1984.

Turkey is in the midst of a widening crackdown that began after a failed coup attempt in July 2016. Some 50,000 people have been jailed and 150,000 sacked or suspended from their jobs.

Critics, including rights groups and some Western allies, say Erdogan is using the coup as a pretext to muzzle dissent. The latest arrests have also drawn criticism from the European Union.

Turkey says its measures are necessary due to the gravity of the security threats it faces.

(Additional reporting by Ali Kucukgocmen; Editing by David Dolan and Janet Lawrence)