India's second-largest party has announced it is withdrawing from the country's coalition government.
Muthuvel Karunanidhi, the head of the Dravida Munnetra Kazhagam (DMK), told a news conference in the city of Chennai on Tuesday that his party would pull out of the left-leaning United Progressive Alliance (UPA) coalition, in power since 2009.
The DMK, a regional party from the state of Tamil Nadu, had been pressuring the government to condemn Sri Lanka for alleged war crimes against ethnic minority Tamils during the island's civil war.
"If we continue to remain in the government, it will be the most harmful to Tamil people as the government is not doing anything useful to solve the crisis," said Karunanidhi.
The party, which depends on Tamil voters who have close ties to their counterparts in neighbouring Sri Lanka, is the second-biggest coalition member with 18 members of parliament and has five mostly junior positions in cabinet.
It has threatened in the past to withdraw from the coalition without following through.
If it pulls out, the government would be more vulnerable to falling before for elections planned for the first half of 2014.
'Government in disarray'
But analysts said the loss of the DMK's support would be unlikely to trigger polls in the short term as the UPA has secured support from outside allies to pass legislation.
"No one expects the government to fall, but the drop in numbers will affect its stability," Parsa Venkateshwar Rao, a political columnist for the DNA daily newspaper, told the AFP news agency.
"The picture is that this government is in disarray, facing crisis after crisis."
The UPA is dominated by the Congress party run by the Gandhi political dynasty and has technically been a minority in parliament since September when another regional party withdrew.
Finance Minister P Chidambaram told reporters on Tuesday that the government remained "stable" and Karunanidhi might be persuaded to stay if parliament passed a resolution condemning Sri Lanka.
"He will review his decision if that resolution is brought before cabinet," he told reporters.
The instability comes amid a sharp slowdown in economic growth, which has slipped to decade lows, and could affect the government's declared intention to introduce more pro-market reforms.