MK Stalin said PM Modi is leading a dictatorial rule which is worse than emergency.
The DMK on Monday hit back at Prime Minister Narendra Modi for describing its alliance with the Congress as "opportunistic" and asked if the BJP's reported attempts to join hands with its rival AIADMK was indeed ideology based.
The ruling AIADMK lashed out at MK Stalin for his remarks, saying it was not in any alliance.
Responding to PM Modi's criticism of the DMK-Congress tie-up as "opportunistic," Mr Stalin said, "There are reports that PM Modi is trying to strike an alliance with the AIADMK. Is it an alliance of ideology or loot is my question?"
He has been often critical of the ruling AIADMK in Tamil Nadu, with his party levelling repeated charges of corruption against it, including chief minister K Palaniswami.
Mr Stalin also alleged that PM Modi had tried to ensure the merger of the earlier rival factions headed by AIADMK leaders Palaniswami and O Panneerselvam.
Post their merger in August 2017, Mr Panneerselvam was made deputy to Mr Palaniswami.
On Sunday, PM Modi had recalled the past rivalry between the Congress and its southern ally DMK, and said no one had forgotten where the two parties stood on the Jain Commission.
"That time Congress said either it is DMK or it is us. But today they are together. If not opportunism, what explains their alliance," he asked.
Responding to Mr Stalin's criticism, senior AIADMK leader D Jayakumar accused the DMK and Congress of being "responsible" for the failure to prevent mass Tamil civilian casualties during the Sri Lankan ethnic strife in 2009.
He indicated that then chief minister, the late DMK president M Karunanidhi, wielded tremendous clout in the Congress-led UPA government but did not do anything on the matter.
"What name can be given to that alliance (between DMK and Congress) -- a murderous alliance. This is the name the people of Tamil Nadu have given to them," he told reporters.
The AIADMK was not holding any alliance talks right now and such matters will be decided by the party leadership, and the decision-making bodies of General Council and Executive, he said.
"Why is he (Stalin) giving certificate as if we have entered into an alliance," Mr Jayakumar said and accused Mr Stalin of making such comments based on "assumption."
Mr Stalin, when asked about criticism of DMK joining hands with the Congress despite it being a victim of Emergency, said BJP-led rule "is worse than the Emergency."
He said former Prime Minister Indira Gandhi, who had implemented Emergency, had later "expressed regret for that.That is democracy. But today Modi is leading a dictatorial rule which is worse than Emergency," he said.
In his interaction with party workers Sunday, PM Modi had said many leaders in the 'mahagatbandhan' were "arrested and tortured" during the Emergency, without naming anyone.
Mr Stalin was one of the leaders incarcerated during the Emergency. Many other DMK leaders were also jailed then.
Mr Jayakumar hit out at the DMK over this also, saying though DMK leaders were jailed during the Emergency, M Karunanidhi later aligned with late Indira Gandhi though he had made very critical and "demeaning" remarks against her.
On his proposal to project Rahul Gandhi as the Prime Ministerial candidate of the opposition for next year's polls, Mr Stalin said he had only expressed DMK's "feeling."
"None has opposed this feeling. Only, there are opinions that this could have waited and the announcement made after some time," he said.
"I am confident that soon those who are making such remarks will also wholeheartedly accept this," and support the idea, he said.
West Bengal Chief Minister Mamata Banerjee, the TMC supremo, has said the topic could be discussed only after the 2019 Lok Sabha election and once the opposition alliance emerged winners.
Similary, Samajwadi party leader Akhilesh Yadav has said Mr Stalin's proposal may not necessarily be the opposition alliance's opinion.
Mr Stalin had made the "Rahul for PM" pitch ahead of the Lok Sabha polls last week at a DMK organised public rally.