Sri Lankan forces, shooting indiscriminately, stormed a church where hundreds of Tamils were taking shelter Saturday, and then opened fire in the surrounding village, killing five people and wounding dozens, witnesses said.

The government denied the accusation and blamed Tamil Tiger rebels, but numerous witnesses and an international aid worker said Sri Lankan forces were responsible for the deaths as the island nation appeared to stumble even closer toward all-out war.

CountryWatch: Sri Lanka

The killings came hours after the Tigers had assaulted a navy base in the same remote northwestern fishing village, Pesalai, triggering a naval and helicopter battle that in turn prompted the Tamils to seek refuge in the church where they were attacked.

The surging violence — which included the arrest near the capital, Colombo, of two suspected Tamil Tiger bombers who swallowed cyanide after their capture — heightened fears that Sri Lanka could return to an all-out civil war.

The past few days have seen by far the worst violence since an often-violated cease-fire was signed in 2002 by the government and the Tamil Tigers, who control much of Sri Lanka's north and east.

The rebels, formally called the Liberation Tigers of Tamil Eelam, have been fighting for more than two decades to create a homeland for the country's 3.2 million predominantly Hindu Tamils, a minority that has faced decades of discrimination at the hands of the largely Buddhist Sinhalese majority, who account for 14 million of Sri Lanka's people.

The civil war killed more than 65,000 people before the cease-fire, and as talks to build on the truce have faltered, sporadic shootings and bombings in and around Tiger strongholds have escalated into near-daily violence.

In a hospital in Mannar, near Pesalai, many injured villagers gave near-identical accounts of security forces indiscriminately shooting into the Our Lady of Victory Roman Catholic Church, then opening fire in the village.

"We were all inside the church when the navy and army broke in and opened fire. A grenade was thrown inside through a window," said Mariyadas Loggu, 46, who was being treated for hand injuries. "If this is what the people responsible for security do, where else can we go?"

Villagers often take shelter from the area's violence in churches, seeing them as safe havens.

One person died in the church Saturday and four others were fatally shot while returning from fishing, Loggu and a half-dozen other hospitalized villagers said.

An Associated Press reporter at the Mannar hospital counted 47 Pesalai villagers injured in the violence.

Reporters were unable Saturday to reach Pesalai, which was sealed off by government roadblocks.

An international aid worker, who said he had visited Pesalai and interviewed survivors, backed their account of the incident. He spoke on condition of anonymity, saying he did not want to hurt relations with the government. The aid worker also said the military had burned more than two dozen wooden fishing boats.

The military rejected the accusations.

"The LTTE has done it. We do not target civilians," said Commander D.K.P. Dassanayake, a navy spokesman.

He said the Tigers had stormed the village in 12 boats, first firing grenade launchers at the police station, which is near the navy base and church.

Eight Tiger boats, which normally carry three or four fighters, were destroyed, and three navy vessels were damaged, he said, adding that air force helicopters also fired on rebel boats.

Navy officials said the bodies of three sailors had been recovered, and eight more were missing. They said up to 30 guerrillas had been killed.

But the rebels' main Web site said four government naval boats had attacked Tiger vessels, and that three of the four were sunk, killing 12 government soldiers and leaving just two Tigers with minor injuries.

The rebel attack came after Sri Lanka's military unleashed retaliatory strikes on rebel positions in the north and east Thursday and Friday for a bus bombing that killed 64 people.

The government blamed the Tigers for the bombing, the worst act of violence since the cease-fire. The rebels denied involvement.

On Friday, in the town of Ja-Ela, just north of Colombo, witness Paul Jayamaha said he heard two explosions at sea and then saw two men swimming to shore who were caught by fishermen.

Both men swallowed cyanide capsules, were admitted to a hospital and later handed over to police, hospital director Dr. R.M. Rajamanthri said.

The Tigers often wear cyanide capsules around their necks so they can kill themselves before being captured and interrogated by the government.

Police found oxygen bottles and underwater swimming gear washed ashore, Jayamaha said.

The discovery of the equipment and the explosions suggested the captured men had been on a suicide attack mission, said Deputy Inspector General of Police N.J. Illangakoon.