COLOMBO, Sri Lanka -- Government forces bombed rebel Tamil Tiger positions yesterday after a pair of powerful mines ripped apart a civilian bus and killed 68 people in the deadliest attack since the two parties declared a truce four years ago.
The violence heightened fears of a return to civil war in this island nation, despite both sides' insistence that their official cease-fire agreement remained in effect.
Keheliya Rambukwella, a government defense spokesman, said there was no formal resumption of hostilities but, "We will have to take a serious re-look at the agreement owing to the attack."
The rebels, known as the Liberation Tigers of Tamil Eelam, denied responsibility for the bus explosion. In a statement, the group accused Sri Lankan forces of orchestrating the attack "with the sole aim of blaming the LTTE."
However, the two Claymore mines used in the attack were similar to those that the rebels have deployed against the military in a series of attacks and counterattacks in the past several months that have left 700 people dead and the cease-fire in tatters.
Yesterday's explosion struck a bus crammed with commuters and schoolchildren in the northern town of Kabithigollewa, an area bordering territory controlled by the insurgents.
Rambukwella said the explosion was a deliberate attack on civilians and not a rebel assault on soldiers gone awry.
"This was not an accident, as the army does not use this road, he said. So the motive was very clear."
The mines were apparently hung from trees, rather than planted in the ground, for maximum impact - a tactic commonly employed by rebel fighters. The explosives were packed with ball bearings to inflict heavy damage and detonated by remote control. The blast flipped the bus over, trapping passengers inside, witnesses said.
"There was blood and body parts everywhere," survivor Chintha Irangani told Reuters news agency. "I fell unconscious. I saw my children's bodies at the hospital."
Among the dead were 15 youngsters, authorities said. The victims were primarily Sinhalese, the ethnic group that dominates Sri Lankan politics and forms the majority in the southern and western part of the country.
The rebels' goal is to establish a separate homeland in the north and east for the island's minority Tamils.
Within hours of the attack, the Sri Lankan air force bombed Tamil Tiger positions in the north. The rebels also came under artillery fire in the east, near the port city of Trincomalee. There was no word on casualties among rebel forces.
Each side accused the other of engineering yesterday's violence to stoke ethnic unrest in a brutal conflict that has claimed more than 64,000 lives since 1983.
Peace seemed to be on the horizon in 2002 when the government and the Tamil Tigers agreed to lay aside arms and negotiate. Several rounds of talks have been held, most recently in February.
But the peace process broke down amid escalating attacks by rebels and by what critics say is government foot-dragging in addressing Tamil grievances.
Last week, a planned meeting in Oslo to discuss the Nordic mission monitoring the cease-fire ended before it began when Tamil Tiger negotiators refused to sit down with Sri Lankan government representatives.
The insurgents also are angry at the European Union's recent decision to classify their group a terrorist organization, after the lead of the United States, Canada and Britain.
Late last month, a diplomatic coalition including the U.S. urged the rebels to renounce violence and return to the negotiating table.
At the same time, it warned the government that billions of dollars of foreign aid to Sri Lanka could be in jeopardy if officials did not address Tamil demands and stop attacks on the rebels by rogue armed groups.
Henry Chu and Easwaran Rutnam write for the Los Angeles Times.
Some earlier developments in Sri Lanka's conflict:
1975: Liberation Tigers of Tamil Eelam forms, demands a separate state for minority Tamils in island's north and east.
1983: Civil war begins, sparked by anti-Tamil riots in Colombo that many believe were organized by Sinhalese-dominated government.
1991: Female Tamil Tiger suicide bomber assassinates India's former prime minister, Rajiv Gandhi, apparently in revenge for sending Indian peacekeeping troops who ended up fighting the rebels.