The DMK had earlier called K Annamalaai's allegations "a joke".
The Tamil Nadu government today filed a defamation case against the state BJP chief K Annamalai for his "DMK files". The city Public Prosecutor has alleged that Mr Annamalai is defaming Chief Minister MK Stalin.
The BJP leader had recently alleged that MK Stalin was paid Rs 200 crore in 2011 to fix a Chennai Metro contract. Claiming that leaders of Mr Stalin's party, the DMK, own assets worth Rs 1.34 lakh crore, earned through corrupt means, Mr Annamalai also alleged the Chief Minister's family members were directors of a Dubai company that's investing in the state.
DMK Spokesperson TKS Elangovan told NDTV, "The best step is to punish Annamalai. What Rahul Gandhi said was nothing, but he has been disqualified. When they can do that, there is ever reason to file a suit against Annamalai".
The BJP has said Mr Annamalai, who refused to apologise after DMK's legal notice earlier, will fight the case in court.
The BJP Tamil Nadu chief had on April 14 this year made public a long list of assets worth Rs 1.34 lakh crore which he claimed are owned by key DMK leaders including Chief Minister MK Stalin's son and Sports Minister Udhayanidhi Stalin, and other ministers including Durai Murugan, EV Velu, K Ponmudy, V Senthil Balaji, and former Union Minister S Jagathrakshakan.
The DMK had then called Mr Annamalaai's allegations "a joke".
"There is not a single allegation of payment of bribe. All candidates he has listed have given their asset details in their affidavits. If there is even one violation, any citizen can challenge the election," DMK MP RS Bharathi had said.
On April 20, K Annamalai cited an audio clip on social media claiming that state Finance Minister Palanivel Thiaga Rajan, in conversation with someone, revealed that Chief Minister Stalin's son Udhayanidhi Stalin and son-in-law V Sabareesan accumulated wealth Rs 30,000 crore in a year.
Later, on April 25, the BJP leader released an audio clip that allegedly features Palanivel Thiaga Rajan's voice. The man in the clip can be heard accusing Chief Minister MK Stalin's family of corruption.
Two days later, Palanivel Thiaga Rajan released a statement refuting the claims and dismissing the audio clip as "malicious, fabricated" and released just to create division among DMK cadres and drive a wedge between him and the Chief Minister.