COLOMBO: An unrelenting hail of artillery in Sri Lanka's war zone killed at least 378 civilians, according to a government doctor who survived the attack as shells flew near the makeshift hospital. More than 100 of the victims were children, the U.N. said Sunday.

A rebel-linked Web site blamed the attack on the government, while the military accused the beleaguered Tamil Tigers of shelling their own territory to gain international sympathy and force a cease-fire.

The attack marked the bloodiest assault on ethnic Tamil civilians since the civil war flared again more than three years ago. Health officials said a hospital in the war zone was overwhelmed by casualties, and the death toll was expected to rise.

Reports of the fighting are difficult to verify because the government bars journalists and aid workers from the war zone, but the U.N. confirmed a heavy toll from the attack.

"It seems beyond dispute that hundreds of civilians were killed overnight including more than 100 children," U.N. spokesman Gordon Weiss said.

The first shells slammed into the tiny strip of rebel-controlled area along the northeast coast Saturday evening, soon after a Red Cross ship that had been evacuating wounded civilians left the area, health officials said.

About 50,000 civilians are crowded into the 2.4 mile- (4 kilometer) long strip of coast along with the Liberation Tigers of Tamil Eelam fighters, who have been fighting for 25 years for a homeland for minority Tamils.

Artillery pounded the area throughout the night, forcing thousands to huddle in makeshift bunkers, said Dr. V. Shanmugarajah, a health official in the region.

Hours after the attack, the dead and wounded continued to pour into the hospital, he said. As of Sunday afternoon, the bodies of 378 civilians had been brought in and were being buried by volunteers, but the death toll was likely far higher since many families buried their slain relatives where they fell, he said.

The rebel-linked TamilNet Web site said rescue workers had counted 1,200 civilians killed in the attack. Among the dead, was the rebels' military spokesman Rasiah Ilanthirayan, according to TamilNet.

Bodies were laid out in rows on the mud outside the hospital, some of their faces covered with mats and sheets, according to photos from the area. One small boy was stripped to the waist, his head covered in a bloody bandage and his mouth agape.

The hospital was struggling to cope with the 1,122 wounded civilians.

The government had recently sent medical supplies, but a shortage of physicians, nurses and aides made treatment difficult, Shanmugarajah said.

"We are doing the first aid and some surgeries as quickly as we can. We are doing what is possible. The situation is overwhelming; nothing is within our control," he said.

More than half the hospital staff did not turn up for work because their homes were attacked and many of the wounded went untreated for more than 24 hours, said another health official, who spoke on condition of anonymity because he was not authorized to speak to the media.

The shelling had subsided early Sunday, but a new bombardment began about 6 p.m., the official said.

Suresh Premachandran, an ethnic Tamil lawmaker, said the assault was the deadliest attack on civilians since the 1983 anti-Tamil riots that killed as many as 2,000 people and helped trigger the civil war.

"In the name of eliminating terrorism, the Sri Lankan government massacres its own citizens. It is absolutely unacceptable," he said, calling for the international community to intervene.

TamilNet also blamed the attack on the Sri Lankan forces, which rights groups have accused of bombing and shelling the war zone despite its pledge to stop using heavy weapons.

The Sri Lankan military denied firing the artillery and said the rebels appeared to be launching mortar shells from one corner of the coastal strip into another section heavily populated with civilians.

"I think the LTTE (Liberation Tigers of Tamil Eelam) is now trying to use these people as their last weapon to show the world that the army is firing indiscriminately and stop this offensive," military spokesman Brig. Udaya Nanayakkara said.

Human rights groups have accused the rebels of holding the civilians as human shields and shooting some who tried to flee.

U.N. figures compiled last month showed that nearly 6,500 civilians had been killed in three months of fighting this year as the government drove the rebels out of their strongholds in the north and vowed to end the war.

The government has brushed off international calls for a humanitarian cease-fire, saying the beleaguered rebels would use any pause in fighting to regroup.

Human Rights Watch on Saturday accused the military of repeatedly hitting hospitals in the war zone with artillery and aerial attacks that killed scores of people and said commanders involved in the attacks "may be prosecuted for war crimes."

Meanwhile, pressure on reporters critical of the government's war effort has intensified.

On Sunday, Sri Lanka deported three journalists for London-based Channel 4 television news who had been arrested on charges of tarnishing the image of the security forces after running a report about alleged sexual abuse in displacement camps.

Lakshman Hulugalle, a government spokesman, said the journalists admitted they had "done something wrong" and would not be allowed to come back to Sri Lanka.

However, Nick Paton-Walsh, the channel's Asia correspondent, denied giving a statement to police or admitting wrongdoing.

"This is complete rubbish," he told The Associated Press from Singapore after his deportation.