COLOMBO, Sri Lanka -- The Sri Lankan military attacked Tamil rebels in the northeast of the island nation yesterday , and the rebels retaliated with artillery and small arms fire in heavy fighting that left 13 combatants dead, officials said. A cease-fire monitor warned that the situation was worsening.
Senior rebel official Seevarathnam Puleedevan said at least 50 civilians were killed and 200 injured in the fighting near a key waterway, but a military spokesman said he was unaware of any civilian casualties.
``The peace process is in grave danger," Puleedevan said.
He appealed to the International Committee of the Red Cross to help evacuate civilian casualties. But Red Cross official Davide Vignati said the organization had not received an official request from either side.
At least six government soldiers were killed and scores wounded , said Dr. B.G.M. Costa, a hospital doctor in Kantale, a town in the area.
A rebel spokesman, Rasiah Ilanthirayan, said seven rebels had died and 15 were wounded.
``It is a warlike situation. Our forces are retaliating with artillery fire and direct gunfire ," Ilanthirayan said.
Robert Nilsson of the Sri Lanka Monitoring Mission said the situation was worsening. ``Hopefully, there will be a change of heart. This has already gone too far," he said.
Battles have centered on a key reservoir and canal in Trincomalee district, which in recent weeks has seen some of the worst fighting since the country's 2002 cease-fire.
Estimates of the number of combatants and civilians killed range from about 100 to 300.
Military spokesman Major Upali Rajapakse said he knew of no civilian casualties in yesterday's action, but charged that the rebels often use civilians as human shields and place gun positions around villages.
``The Sri Lankan Army does not target civilians," he said.
The rebels closed sluice gates at the reservoir on July 20, cutting water to more than 60,000 people living in government-controlled villages after accusing the government of reneging on a pledge to boost water in rebel-held areas.
The rebels said on Tuesday that they were reopening the gates, asserting that attacks on rebel areas by army troops were hurting civilians.
The military said Wednesday that it had reclaimed control of the waterway. But the government resumed shelling around the reservoir the same day, saying it needed to clear the area of rebels so they would not block the water supply again.
``The Sri Lankan Army has launched a full-fledged offensive operation against our territories involving thousands of troops, heavy guns, and bombardment," Ilanthirayan said.
The Tamil Tigers began fighting in 1983 for a separate homeland for 3.2 million Tamils, accusing the country's 14 million Sinhalese of discrimination.
The 2002 cease-fire put a temporary halt to the bloodshed, but the truce has nearly collapsed in recent months.
Renewed fighting has killed more than 900 people, half of them civilians, since December, cease-fire monitors say.
In Geneva, meanwhile, the top U N humanitarian official, Jan Egeland, demanded an independent investigation into the slaying of 17 international aid agency workers whose bodies were found in the past week. The 16 Tamils and one Muslim, working for Action Against Hunger, had been doing post-tsunami relief work in Sri Lanka.
``We're now demanding an independent investigation in Sri Lanka [into] how this could happen, execution-style, to humanitarian, unarmed workers," Egeland said.