A human rights group is asking Sri Lanka's government to investigate the killing of a senior Tamil Tiger rebel earlier this week. The rebels say the latest violence will hurt efforts to put an end to a two-decade-long civil conflict in the country.
Human Rights Watch says the killing of a Tamil Tiger rebel leader in an ambush on Monday may signify "a dangerous new round of politically motivated violence".
E. Kausalyan, the senior-most rebel leader in the east of the country, was shot and killed along with five others as his vehicle traveled through a government-controlled area.
A breakaway faction of the rebel group has claimed responsibility for the killing. The Tigers accuse the faction of collaborating with government troops, and have warned that the violence will hamper efforts to restore peace in the country.
The government has denied the allegations and condemned the killings. Human Rights Watch has called for a transparent investigation into the deaths.
The rights group also accuses the rebels of carrying out politically motivated crimes. It says there has been a spate of killings and abductions in recent months of both rebels and their opponents.
Jehan Perera, head of Sri Lanka's National Peace Council, says such violence had halted after much of the country was devastated by the December tsunami. But he says political killings appear to have resumed.
"The tsunami brought these killings to an end for six weeks," said Jehan Perera. "And in those six weeks we began to have the hope, or the illusion, that the problem was behind us. Now we are back again to reality and square one, and that is that this is a country and a conflict in which assassination has been used as a tool of politics, of getting ahead, of defeating the opponent."
Before the December 26 tsunami, rising political violence had put a strain on a fragile three-year ceasefire, and raised fears of a return to armed hostility.
But in recent weeks, both sides vowed to put aside politics and concentrate on reconstruction of the country.
Some analysts fear this week's killing could spawn acts of retaliation and erode peace hopes.
At the core of the country's civil conflict are complaints of discrimination against the minority Tamil community by the majority Sinhalese. Although a truce is in place, peace talks have been deadlocked for nearly two years over the rebels' demand for interim self-rule.