Sri Lanka's Tamil Tigers said they raided camps belonging to renegade ex-rebels on Sunday, killing 20, while the government and rebels traded artillery fire in the north-east as war fears remained high.
The past three weeks have been the bloodiest since a 2002 cease-fire with more than 120 people, possibly many more, killed in suspected Tiger attacks on the military, ethnic riots, government air strikes and murders of civilians on both sides.
The rebels say the government uses fighters led by former Tiger eastern commander Karuna Amman as "army-backed paramilitaries" to attack the mainstream Liberation Tigers of Tamil Eelam (LTTE) - a charge the government denies.
"It is a very severe blow for the paramilitary groups and for the Sri Lankan army," head of the Tiger peace secretariat S. Puleedevan told Reuters by satellite phone from rebel territory. He said the camps were in army-controlled areas.
"We have burnt the camps and a lot of arms and ammunition provided by the Sri Lankan army," he added.
He said the rebels had come under artillery fire from nearby army camps during the attack, but were withdrawing back behind their own lines with only one Tiger fighter wounded. Twenty Karuna fighters were killed and 15 wounded, he said.
A Karuna aide confirmed the attack but disputed figures, telling Reuters only five had been killed and seven wounded.
The army denied there had been any shelling, and said all they knew was there had been fighting between Tiger and Karuna forces in jungle areas not really controlled by either side. They have always denied knowing where the Karuna camps were, but Nordic truce monitors said the army, at best, turns a blind eye.
ARTILLERY DUEL: In the evening, the army said they had exchanged artillery fire with rebel positions after seven to eight rounds of Tiger artillery fell on forward army positions in the north-eastern Mullativu district. There were no army casualties, a spokesman said, and the retaliation did not include air strikes.
The army said suspected Tigers also wounded two navy sailors in a claymore fragmentation mine ambush on the northern Jaffna peninsula.
Peace talks due to take place in Switzerland have been indefinitely postponed because of wrangling over the transport of eastern rebel leaders to their headquarters for a pre-talks meeting.