According to TV reports, Karunanidhi alleged, "Atmosphere for communal violence is being prepared."
89-year-old Karunanidhi also warned, "BJP government at the Centre is dangerous."
However, in the past, the former Tamil Nadu chief minister has showered praises on the BJP's prime ministerial candidate Narendra Modi by describing him as hard-worker and a "good friend".
The DMK was once a part of the BJP-led National Democratic Alliance but later switched allegiance to the Congress-led United Progressive Alliance.
Narendra Modi has become a household name in Tamil Nadu.
A section of DMK leaders feels that the threat in the future will be from Narendra Modi and not from Jayalalithaa, and hopes to settle scores with her in March 2016.
Recently, Modi, who has now become a household name in Tamil Nadu, had met Tamil superstar Rajinikanth in Chennai and his eight massive rallies also attracted huge crowds in the state.
Modi has become the talking point among the 60 million Tamils and others in the state and this is for first time that the Congress is not riding on the shoulders of any Dravidian party, and Modi has captured that space.