A suspected Tamil Tiger suicide bomber killed Sri Lanka's highways minister and at least 12 other people attending a marathon race near the capital Colombo on Sunday.
"Minister Jeyaraj Fernandopulle is dead from the explosion," said Laksman Hulugalla, director general of the media centre for national security.
Television footage showed a ball of fire moving towards the minister as he signalled the start of the run.
K.A Karunarathne, a former top marathon runner, was among the dead. About 100 people, some of them runners in the race, were wounded.
Authorities immediately pointed the finger of blame at the Liberation Tigers of Tamil Eelam (LTTE).
"It's a suicide attack, definitely by the LTTE," said a bomb squad official, speaking at the scene on condition of anonymity.
The official said the explosion took place very close to the minister and involved a large quantity of explosives.
The Sri Lankan military has launched an offensive on the LTTE's northern strongholds in which at least 100 rebel fighters were killed last week, the military said.
The rebels have in the past hit back with bombings in Colombo and in the relatively peaceful south of the island when they have come under military pressure in the north and east.
Fernandopulle, 55, was a member of the government negotiating team for failed peace talks with the Tamil Tiger rebels two years ago.
Sunday's attack took place in the town of Weliveriya, 30 km from Colombo, where Fernandopulle had gone to flag off the marathon.
