The supporters, who hurled petrol bombs and stones at the building, were protesting a survey published by the Maran family-owned newspaper on who could be Karunanidhi’s ‘possible political heir’.

The survey “Makkal Manasu” (What people think) conducted by the daily in association with A C Nielsen, gave 70 per cent chances to M K Stalin, the second son of Karunanidhi and just two per cent to Azhagiri, who controls party cadres in the southern districts, and Kanimozhi, the CM’s daughter. The daily is owned by Karunanidhi’s grand nephew Kalanidhi Maran, brother of Union Minister Dayanidhi Maran.

The survey also gave 20 per cent chance to the category ‘Others’ (31 per cent in Chennai). This made Azhagiri supporters believe that Dayanidhi Maran was being projected as the second choice after Stalin.

Madurai police said two computer service engineers, Gopinath and Vinod Kumar, who were trapped inside the building, died of asphyxiation. Several hours later, the charred body of a watchman was also found. Police said 25 people were taken into custody in connection with the deaths and violence.

Elsewhere in Madurai and surrounding districts, Azhagiri supporters continued to set fire to copies of Dinakaran, also blocking traffic at several places. They stoned public transport buses, damaged several vehicles and disrupted normal life.

The violence comes just two days before celebrations being organized to mark 50 years of Karunanidhi in the state Assembly, with an array of leaders, including Congress president Sonia Gandhi, Prime Minister Manmohan Singh and Lok Sabha Speaker Somnath Chatterjee, expected to participate.

Karunanidhi was said to have been so disturbed by the violence that he wanted to call off the function. But his allies insisted that the celebrations should take place as scheduled.

Condemning the violence and announcing relief of Rs 2 lakh each for the families of the three men killed in the attack, Karunanidhi said: “I also promise appropriate legal action against those involved, whoever they be. I join my friends from the media in condemning this attack.”

Pointing out that he had expressed disapproval of an opinion poll in Dinakaran which rated Dayanidhi Maran as the ‘best’ Union Minister from Tamil Nadu, Karunanidhi regretted that another survey by the newspaper on his possible successor had led to the loss of three lives. The DMK, he said, was a democratic party and did not elect its leaders based on heredity.

DRAVIDIAN DYNASTY

Contenders for Muthuvel Karunanidhi's political legacy

M K Stalin, 55

Who: Karunanidhi's second son. Groomed to take over from father. Ex-Chennai mayor, now Minister. Strongest contender for leadership.

Clout: Top party posts and key Cabinet portfolios packed with Stalin's men. After father, has majority support of party cadres.

M K Azhagiri, 57

Who: Karunanidhi's eldest son. Has never held a party post.

Clout: Rules Madurai and southern districts like his fiefdom. Karunanidhi has been very clear that his elder son would take care of party affairs in the south, but would not hold any post. This is only to ensure a smooth succession for Stalin.

Dayanidhi Maran, 39

Who: Karunanidhi's grand nephew, and Union Telecom Minister. Son of former Union Minister Murasoli Maran

Clout: Karunanidhi hoped Dayanidhi would lobby for DMK in Delhi. Has little by way of party base.

Kanimozhi, 39

Who: Karunanidhi's daughter by his 'second wife' Rajathi Ammal, the poet. Anointed by her father as his 'cultural heir'.

Clout: While the MK brothers, Stalin and Azhagiri, are keen to see Kanimozhi take on a more substantial role in Delhi, she has kept away from political limelight so far.