Police take leftist Ozgur Radio employees Sinan Gercek, Metin Ozalp, Mine Ozalp and Izmır's Demokrat Radio's coordinator Nadiye Gurbuz into custody.
The allegations remain unknown as the case is regarded as classified by court, lawyers of the defendants told bianet.
Officers from Counter Terrorism Unit of the Istanbul Police Department raided houses of the accused early this morning.
Ozgur Radio issued a written statement, condemning this act as a part of "the ongoing pressure to silence socialist media".
Four people are under investigation linked to a previous operation against the illegal Marxist Leninist Communist Party (MLKP), the police claimed.
"A report have been filed to investigate Ozgur Radio's revenues following the police operation in 2006" said lawyer Filiz Kilicgun. "We have yet to see the case file as it remains classified. So we don't know the exact allegations and can't inform our clients."
Radio workers can remain under custody up to four days. Gurbuz will also be brought to Istanbul for rendition. Police have confiscated several computers during the raid.
In 2006, 23 people have been arrested and tried with jail sentences. Among them were Ozgur Radio editor-in-chief Fusun Erdogan, Atilim newspaper editor-in-chief İbrahim Cicek and news coordinator Sedat Senoglu.(EÖ/AGÜ)
