The party's announcement came even as Prime Minister Manmohan Singh said that India was "inclined to" vote in favour of a resolution on Sri Lanka which meets "our objectives" with regard to the future of ethnic Tamils.
DMK's announcement comes despite Prime Minister Singh assuring that India was "inclined to" vote in favour of a resolution on Sri Lanka.
"We welcome the announcement (by Singh) if it is true. We will wait for the final decision," said Karunanidhi.
Karunanidhi also appealed to that the country come forward in support for the resolution.
"The fast will be held seeking India should come forward to support the resolution which calls for investigating war crimes by the Sri Lankan government which continued to kill Tamils even after the end of the war," Karunanidhi said in the statement.
The statement said that the DMK supremo would lead the fast from Chennai, while details of rest of the state would be given later.
"The resolution should cover India's objectives to achieve a future for Lankan Tamils based on equality, dignity, justice and self respect," said Prime Minister Manmohan Singh.