A rebel homicide bomber attacked a procession of Muslims celebrating a religious holiday Tuesday in southern Sri Lanka, killing 14 people and critically wounding a government minister, officials said.

Officials blamed the Tamil Tigers for the blast, saying the rebels had grown desperate in the face of a relentless government offensive that has brought them to the brink of defeat after more than a quarter century of civil war.

Meanwhile, heavy artillery attacks in the war zone Tuesday killed at least 49 ethnic Tamil civilians and wounded hundreds of others, the top government health official in the war zone said.

Human rights groups and aid workers have expressed growing concern for the fate of the tens of thousands civilians trapped in the conflict zone amid the escalating violence.

As the fighting raged in the north, the homicide bomber struck in the southern town of Akuressa, apparently targeting six ministers as they led a procession toward a mosque to celebrate Mawlid, which commemorates the prophet Mohammed's birthday.

Television footage showed men in white robes and caps slowly parading down the street before the blast sent them running in all directions. Charred, twisted bodies filled the street, their clothes nearly incinerated by the explosion just outside the mosque compound's gates.

"I heard a huge sound, and then I saw people had fallen everywhere. They were covered with blood and flesh, and the wounded people were screaming," Ahamed Nafri, 29, said by telephone from the hospital in the nearby town of Matara.

Police and bystanders were seen lifting the badly bleeding Minister of Posts and Telecommunications Mahinda Wijesekara into a van.

Aruna Jayasekera, a doctor at Matara hospital, said Wijesekera was in critical condition and had been airlifted to the capital for surgery to remove "blood and foreign objects" from his brain.

Another 41 people wounded in the blast were being treated in Matara, he said.