In the latest attack, a roadside bomb tore through a crowded passenger bus as it traveled along a heavily guarded road near rebel-held territory in northern Sri Lanka on Wednesday night, killing 16 people and wounding 22 others, officials said.
The bombing, which the government blamed on the rebels, was carried out despite a major security crackdown following blasts at a government office and a department store last week that killed 20 people.
Government officials said the new round of attacks on civilians proved the rebels were growing increasingly frantic in the face of a military offensive on their power base in the jungles of northern Sri Lanka.
"That means they are weak and desperate," Media Minister Anura Yapa told reporters Thursday.
"We are trying our level best to destroy these terrorists in their own areas," he said. "We want to make sure that they are wiped out from the country."
The rebels have been fighting since 1983 for an independent homeland for minority ethnic Tamils in the north and east following decades of discrimination under governments dominated by the Sinhalese majority. More than 70,000 people have died in the conflict.
Fighting has raged in recent weeks along the front lines separating the rebels' de facto state in parts of the north from government-held territory.
In the latest fighting, government troops killed five rebels in two battles Wednesday, the military announced Thursday. Since Saturday, 158 rebels and 21 soldiers have been killed, according to military figures.
Rebel spokesman Rasiah Ilanthirayan could not be reached for comment, and independent confirmation of casualties was not available due to restricted access to the conflict zone. Each side routinely exaggerates the other's casualties and plays down its own.
The bus bombing Wednesday occurred around 8 p.m. as the vehicle traveled north from the agricultural town of Kabithigollewa about 275 kilometers (170 miles) north of Colombo , said military spokesman Brig. Udaya Nanayakkara.
Evening buses in the area are often crowded with farmers returning from a town market. The road, which is bordered by dense bushes and other vegetation, is guarded by military bunkers placed every 400 meters (yards).
The road was sealed off after the bombing and a military search for the attackers began almost immediately, witnesses said. When the road was reopened Thursday morning, a crowd of people began yelling at police, accusing them of failing to protect them.
Nearly 2,000 people gathered at the hospital Thursday in the nearby town of Anuradhapura to visit the injured and find out if their relatives were among the dead. When families were called in to identify bodies at the morgue, piercing wails echoed across the courtyard.
A similar bus attack in the same area killed 64 people last year and provoked a wide-scale military retaliation against the rebels.