Turkish police have detained 235 people for acting on behalf of the outlawed Kurdistan Workers Party (PKK), the interior ministry says.
Those detained include officials from the main Kurdish People's Democratic Party (HDP).
The arrests come two days after twin bomb attacks near a football stadium in Istanbul which killed 44 people.
Meanwhile, Austria says that talks with Turkey over membership of the European Union should be suspended.
A statement from the interior ministry says the operation covered 11 provinces across Turkey from the northwest to the southeast, and targeted people suspected of "spreading terror group propaganda".
It is not clear whether Monday's arrests were directly related to the bomb attacks.
'Scourge of terrorism'
Speaking in parliament, Turkish Health Minister Recep Akdag said most of the 44 people killed on Saturday were policemen.
"It is very painful that we lost 36 of our police officers and eight civilians in a bloody attack," he said, according to Dogan news agency.
The Kurdish militant group TAK, an offshoot of the PKK, said in a statement it had carried out the attack.
President Erdogan told reporters on Sunday that Turkey would fight "the scourge of terrorism to the end", and promised that the attackers would pay a "heavy price".
Last month, 10 HDP lawmakers - including co-leaders Selahattin Demirtas and Figen Yuksekdag - were arrested, causing international alarm.
Speaking ahead of a meeting with his EU counterparts in Brussels, Austrian Foreign Minister Sebastian Kurz said that Europe could no longer ignore President Erdogan's crackdown on the opposition.
"In the last few years, Turkey has drifted more and more away from Europe and in the past few months this trend has picked up speed. More than 100,000 have been arrested," he said.
"Those who are dissenting are being intimidated and the death penalty is to be brought back. Europe has to react. The European parliament in my view did this courageously: they demanded the accession talks to be suspended. I share this assessment."
2016 Kurdish attacks in Turkey
17 February: TAK attack on vehicles carrying general staff personnel in Ankara kills 28 people
13 March: 37 people are killed by TAK militants in a suicide car bombing in Ankara
8 June: TAK bomb attack in Istanbul kills seven police officers and four civilians
30 July: Turkish army base attacked in south-east - unconfirmed reports say soldiers killed some 35 Kurdish fighters who tried to storm the base
9 October: Car bomb attack by PKK militants on checkpoint in south-east kills 10 soldiers and eight civilians