Renegade Tamil militants killed at least four members of the Tamil Tiger rebel group in eastern Sri Lanka on Tuesday, police said, a day after one of the country's top generals was assassinated.
A breakaway faction of the Tigers was suspected in the attack early on Tuesday in the town of Vakarai in the Batticaloa district, the area's police chief Nihal Karunaratne said.
The area where the attack took place is under the control of the mainstream rebels.
The rebel movement split in 2004 when a powerful rebel leader, based in the country's east, broke away from the mainstream group, headquartered in the north.
The Tamil Tigers accuse the Sri Lankan military of aiding the renegades, a charge the military denies.
The violence was the latest in an upsurge of attacks in recent weeks that has threatened to scuttle a four-year cease-fire between the rebels and the government.
On Monday, a suicide bomber killed Sri Lanka's third-highest ranking military officer, Maj General Parami Kulatunga, who commanded many combat operations against the rebels.
Authorities blamed the mainstream Tamil Tiger rebels for the attack, but President Mahinda Rajapakse urged calm and said his government would "act with patience."
In response, the military set up new roadblocks Tuesday in a security clampdown on the capital.
Separately, a Tamil politician opposed to the Tamil Tigers was critically wounded in an attack in Jaffna late Monday, a local police officer said, speaking on condition of anonymity.
Manickam Kanagaratnam, 70, was admitted to a hospital with bullet wounds. The Tigers fought for nearly two decades to carve out a separate homeland for the country's minority ethnic Tamils, who are mostly Hindu, claiming discrimination by the mainly Buddhist Sinhalese majority.
A Norway-brokered truce halted the fighting in 2002 but has virtually fallen apart in recent months, renewing fears of a resumption of all-out civil war that has already killed 65,000 people in the island nation.
The Tigers, formally called the Liberation Tigers of Tamil Eelam, or LTTE, denied taking part in Monday's suicide attack. An insurgent leader, Seevaratnam Puleedevan, insisted the Tigers were abiding by the cease-fire and were committed to peace.
Many analysts were sceptical.
"There is one important lesson that we learn, unlearn, relearn and sometimes forget ... the LTTE does not want peace, does not understand peace, does not know the basic principles of democracy and civilized conduct," the state-run Daily News said in an editorial on Tuesday.
Many Sri Lankans have become increasingly pessimistic. "War is here already -- whether it has been declared officially or unofficially," Pramod Samaratunga, a 27-year-old computer programmer in Colombo, said after Monday's attack.