Suspected Tamil rebels have abducted two members of a rival group of former separatists from their office in a northern town, the Defence Ministry said on Thursday.
A group of armed men stormed into the office of the Peoples' Liberation Organisation of Tamil Eelam in the seaside town of Puttalam late on Wednesday and seized Pakaisara and Karikalam, an official at the ministry's Media Center for National Security said.
Tamils often use only one name.
Remaining members of the former rebel group, which renounced violence decades ago and joined the political mainstream, told Puttalam police that Tamil Tiger rebels abducted the two men, the officer said on condition of anonymity because of army regulations.
Calls to the rebels' headquarters in the northern district of Kilinochchi rang unanswered on Thursday.
Several armed Tamil separatist groups were formed when the campaign for an independent Tamil homeland in Sri Lanka's north and east began in 1983.
Most of those groups, including the Peoples' Liberation Organisation of Tamil Eelam, laid down their weapons and sought a peaceful solution in 1987 under an India-brokered deal.
But the Tamil Tiger rebels, formally called the Liberation Tigers of Tamil Eelam, have maintained their armed campaign and occasionally target members of rival Tamil parties, accusing them of collaborating with government forces to fight the rebellion.
The rebels are fighting to create a separate homeland for Sri Lanka's 3.1 million ethnic minority Tamils, citing discrimination at the hands of the majority Sinhalese.
The government says it can give limited autonomy to Tamils but only within a united Sri Lanka.
Sri Lanka's two-decade-long civil war ended in 2002 when Norway brokered a cease-fire, but the truce has recently come under serious threat due to almost daily violence.
More than 3,500 combatants and civilians have been killed in fighting this year, according to the Defense Ministry. There have been several cases of abductions.