Chennai/New Delhi: The DMK Tuesday quit the UPA voicing regret over India's stand on Sri Lanka at the UNHRC but government leaders insisted there was no threat to the ruling coalition.
DMK chief M. Karunanidhi announced that his party was leaving both the multi-party coalition and Prime Minister Manmohan Singh's government after New Delhi's failure to take a hard line against Sri Lanka.
"Continuing in this government will be an injustice to the Sri Lankan Tamils," the former Tamil Nadu chief minister said in Chennai, and charged Colombo with committing atrocities on its Tamil population.
The 88-year-old politician accused both India and the UN of "betraying" the Sri Lankan Tamils.
The DMK has 18 members in the Lok Sabha and six in the Rajya Sabha. It has five membres in Manmohan Singh's council of ministers.
The DMK's departure still leaves the Congress-led UPA with a simple majority in the 545-seat Lok Sabha but makes it more vulnerable vis-a-vis other allies and an aggressive opposition.
But Karunanidhi made it clear that if the government accepted his two demands - charge Sri Lanka with "genocide" of Tamils and demand a credible investigation into alleged war crimes -- he could reverse his stand.
Karunanidhi said the UPA government had not only refused to consider the DMK's views on the US-sponsored resolution against Sri Lanka at the UNHRC session in Geneva but had quietly watered it down.
DMK's ministers in the government are tipped to resign Tuesday night.
He ruled out extending outside legislative support to the UPA, in which the DMK was the largest constituent after the Congress.
Just before Karunanidhi made the announcement, sparking celebrations by DMK cadres, Congress president Sonia Gandhi used unusually strong language in New Delhi to denounce Sri Lanka.
Addressing party MPs, she alleged that "unspeakable atrocities" had been committed on Tamils in Sri Lanka and that their plight was "very close" to Indian hearts.
"We are anguished by reports of unspeakable atrocities on innocent civilians and children, specially during the last days of the conflict, in 2009.
"That is why we demand an independent, credible inquiry into the violation of human rights in Sri Lanka," said Gandhi, who was widowed in 1991 when a Tamil Tiger suicide bomber assassinated her husband and former prime minister Rajiv Gandhi near Chennai.
Even as the DMK pullout raised questions about the Congress-led United Progressive Alliance's stability, Finance Minister P. Chidambaram brushed them aside.
He said there was no crisis and the government was "absolutely stable" and enjoyed majority in the Lok Sabha.
That did not prevent the stock market from taking a hit. However, Bihar Chief Minister Nitish Kumar said he was confident the UPA would last its five-year term -- until the 2014 Lok Sabha ballot.
Soon after the DMK announcement, top Congress leaders held a crisis meeting.
Chidambaram, one of the three Congress leaders who called on Karunanidhi late Monday, tried to placate him by saying that he was a senior political leader who "deserves all respect".
Asked if the DMK will reconsider its decision, Chidambaram said: "The DMK president has said he will review its decision if a resolution is brought before parliament. We take note of that statement."
The US has introduced a resolution pulling up Sri Lanka over rights abuses and more at the 47-member United Nations Human Rights Council in Geneva.
But the DMK and the AIADMK want India to introduce amendments in the resolution accusing Colombo of committing "genocide" on Tamils during the war against the Tamil Tigers.
On Tuesday, members from both parties disrupted the Lok Sabha and Rajya Sabha demanding a tough Indian stand vis-a-vis Colombo. Meanwhile, street protests against Sri Lanka continued in Tamil Nadu.