DMK leader MK Stalin was arrested along with his supporters outside the collectorate here on Monday for leading a demonstration against the "foisting" of land grabbing cases on partymen by the ruling AIADMK.
Stalin, the former deputy chief minister and younger son of DMK chief M Karunanidhi, and his supporters were, however, released shortly after.
Stalin was briefly detained on Saturday also at Tiruvarur, 325 km from here, during a protest.
DMK held similar protests across the state. Police said the arrests were made when they staging protest without permission.
Lambasting CM J Jayalalithaa for stifling the voice of the opposition, Stalin said: "The DMK will hold more protests and intensify its stir if conditions remain the same."
Ever since Jayalalithaa assumed office in May, DMK functionaries have been facing the heat on land grab charges.