Police in Turkey have launched simultaneous raids in a dozen cities, detaining at least 23 people, according to state media reports.
Those taken in on Sunday include journalists, television producers and police, known to be close to a movement led by Fethullah Gulen, a US-based Turkish Muslim leader.
Turkish authorities accuse Gulen's movement, a former ally, of orchestrating an alleged plot to try and bring down the government.
It says the group's followers were behind corruption allegations that last year forced four cabinet ministers to resign.
A court had issued a warrant to arrest 32 people connected to the group and 23 of them were detained in raids early on Sunday, Anadolu news agency said.
The operation came just two days after Erdogan hinted at a new crackdown against the supporters of Gulen.
Counterterrorism police conducted early morning raids in 13 cities across Turkey, including Istanbul.
Among those named in the arrest warrants was Ekrem Dumanli, the chief editor of Zaman, the country's largest-selling newspaper.
A huge crowd gathered outside the offices of Zaman on the outskirts of Istanbul, forcing the police to
leave the building without detaining any newspaper employees, AFP news agency reported.
"The free press cannot be silenced," the crowd chanted, as Dumanli defiantly addressed them, challenged the police to come and detain him.
As in almost all the previous raids, which targeted mostly police officers, the details of the swoop were leaked by a mysterious Twitter user named Fuat Avni before it was even carried out.
Last week Fuat Avni warned his supporters that police were set to detain up to 400 people, including 150 journalists.
Late on Saturday, he went on to publish the names of those journalists, some of whom were among those rounded up.