Colombo, Sri Lanka: In chilling security camera footage, a female suicide bomber on a mission to kill a Sri Lankan Cabinet minister is seen patiently answering questions in a bustling government office before calmly standing up and detonating the bomb hidden in her bra.

The video, released by police on Friday, gave a rare look at a suicide bomber's last moments and the immediate aftermath of a devastating attack.

In the footage, the bomber, wearing a yellow sari and a white shawl, calmly walked into a small waiting room at the Colombo offices of Social Services Minister Douglas Devananda on Wednesday, the day he sets aside to hear complaints from the public.

The woman, identified by police as 24-year-old Sujatha Vagawanam, sat down in front of a desk and answered questions from Devananda's 72-year-old aide Steven Peiris.

As the two spoke, Peiris was repeatedly interrupted by other officials sitting nearby or walking past.

Security check

After nearly a minute and a half, he began gesturing for her to sit down in a nearby cluster of white plastic chairs, apparently to await a security check. She then stood up facing Peiris, reached her right hand to her right shoulder to grab something and exploded.

Peiris and the bomber, both of whom were killed, flew backward. The others in the room scrambled in all directions, some falling over chairs in their haste to escape as a cloud of smoke hung in the air.

"She thought she was getting caught, so she exploded her bomb," said Devananda, the target of the attack.

Devananda, a Tamil politician seen as a rival to the Tamil Tiger rebel group, said the guerrillas had made more than 10 attempts on his life and killed more than 70 members of his Eelam People's Democratic Party in recent years.

A former Tamil militant group, the Eelam People's Democratic Party renounced violence and joined the political mainstream in 1987. The Tamil Tigers oppose the group.

15 Tamil rebels killed

Troops fought separate gunbattles with separatist Tamil Tiger rebels across Sri Lanka's northern front lines yesterday, leaving 15 guerrillas and three soldiers dead and dozens of combatants injured, the military said.

Army troops destroyed a bunker in the northern Mannar district, southwest of rebel-held territory, killing nine rebels and wounding 47 others, an officer at the Defence Ministry's media centre said on condition of anonymity because he was not authorised to speak on the record. The battle also killed three soldiers and wounded 10 others, he said.

Also yesterday, Tamil Tigers attacked soldiers guarding a defence line that separates government and rebel-held territory in the Muhamalai area of the Jaffna peninsula, the officer said.

Soldiers returned fire, killing six insurgents, he said, adding government forces did not suffer any casualties.