Representative of the ERT employees union Pospert Nikos Tsimbidas confirmed to AFP that he was arrested, while police went through every single room of the building and pushed away some 200 people protesting outside the premises.
The state-run Athens News Agency reported police picked up another three former ERT employees, including the head of Pospert, journalist Panagiotis Kalfagiannis.
Disgruntled former employees have been occupying the building since the government's shock shutdown of ERT on June 11, which made some 2,600 people redundant overnight.
Arguing that ERT ate up 300 million euros (USD 406 million) annually, conservative Prime Minister Antonis Samaras has repeatedly refused to reinstate it in its previous form.
The new broadcaster Nerit is not expected to run before 2014.
Refusing to accept their dismissal, former employees have been maintaining rogue broadcasts from the occupied headquarters, while an interim TV station, DT (Public Television), has been airing from a nearby studio since mid- July.
