Sri Lankan army and the LTTE rebels shelled each other in the island's north on Friday, the rebels and truce monitors said, as the battlefront of the worst fighting since a 2002 truce spread.
The Tigers said troops were trying to breach a "border" that divides government territory from land they control in the northern Jaffna peninsula. They said that fighting that has raged in the east for 17 days was also spreading in the east, and that the air force bombed one of their training camps, killing many.
Truce monitors confirmed artillery exchanges at three points along the border, including the main entry point at Muhamalai where goods travelling by land must pass to reach the army-held Jaffna peninsula -- which is hemmed in by Tiger territory and guarded by 40,000 troops.
"They are firing artillery and trying to breach our borders," Tiger military spokesman Rasiah Ilanthiraiyan told Reuters by telephone from the northern rebel stronghold of Kilinochchi. "They are trying to thrust towards Kilinochchi, so our soldiers are retaliating.
The Tigers said Air Force Kfir jets had pounded rebel positions in the eastern district of Batticaloa, south of the site of a disputed waterway, near which fighting has been concentrated until Friday.
The military said the Tigers had provoked the northern confrontation, and said there was no ground offensive.
"They fired artillery and we are retaliating to their gun positions," said Major Upali Rajapakse, senior coordinator at the National Security media centre. "Our operation to maintain control over the sluice will continue."
An aid worker in Kilinochchi, around 20 miles (30 km) from the border, said the town was tense but quiet. Shelling could not be heard from there.
Army trucks towed heavy gun parts towards the main battle front in the east on Friday after an army camp was wrecked overnight when an artillery piece accidentally exploded, igniting an arms dump.
"VERY DANGEROUS"
The government says it will not halt operations until it controls the disputed sluice and an irrigation reservoir that feeds it. The Tigers say the land is theirs, and say continued army attacks are an effective declaration of war.
"It is definitely very dangerous, opening up on several fronts," said Robban Nilsson of the unarmed Nordic truce monitoring mission. "Guerrilla tactics have always been able to fight the enemy on several fronts, so it is definitely a very worrying development."
North of the town of Batticaloa towards the sluice gate, the Red Cross say at least 15,000 Tamils are displaced behind rebel lines having spent days under shellfire. Other estimates are has high as 30,000 -- but registration has been slow.
"Shells fell nearby," said fisherman Marimuthy Nesan, 24. "We ran. We had no idea. We do not know what happened to our homes. We want peace. That is all."
The Tigers said on Thursday more than 50 civilians had been killed and 200 wounded by army shelling in their territory. Doctors said six troops were killed and more than 50 wounded during an abortive government push to capture the sluice.
The Tigers have long demanded a separate homeland for ethnic Tamils in the north and east of Sri Lanka but President Mahinda Rajapakse has ruled this out. The rebels say any return to stalled peace talks is a distant prospect.
Aid groups accuse the government of forcing civilians to flee Tiger areas by shelling and deliberately blocking aid to thousands of displaced there. More than 30,000 displaced are now housed in cramped, squalid conditions in makeshift camps in army-held territory.
The government is under pressure to allow independent experts to take part in a probe into the execution-style killing of 17 local staff of international aid group Action Contre La Faim. Some relatives of the dead blame troops.
The army denies any involvement in the killings of the aid workers, and blames the rebels. The international community demands answers -- and a return to peace talks.