The former Tamil Nadu chief minister said it was important for India to bring in amendments in the US-sponsored on Sri Lanka in Geneva to demand a probe into "war crimes" in the island nation.
On Friday night, Karunanidhi had said: "India should take steps to amend the American resolution to include that war criminals responsible for the genocide (of Tamils) in Sri Lanka be identified, hold a free international enquiry against them and take time bound appropriate action.
"If this request is not heeded, it will be meaningless for the DMK to continue in the central government," he added.
On Saturday, Karunanidhi admitted that the central government had not responded to his Friday threat.
"That is why we have issued the statement (Saturday). We have given the necessary pressure."
But he added that the DMK had not given any deadline for the central government to spell out its stance in Geneva, where the US sponsored resolution critical of Sri Lanka will come up for vote this month.
India is one of the 47 countries who are members of the current UNHRC. Last year India voted in favour of a similar resolution that berated Colombo for rights abuses and more.
The DMK, with 18 Lok Sabha members, is a key constituent in the central government. It has five members in Prime Minsiter Manmohan Singh's council of ministers.
Sri Lanka is under attack over the death of a large number of Tamil civilians during the end stages of the war that crushed the Tamil Tigers in 2009.
Chennai: DMK chief M Karunanidhi Saturday pressed the central government to take a tough line against Sri Lanka at the upcoming UN Human Rights Council (UNHRC) meet in Geneva.
First Published: Saturday, March 16, 2013, 13:30