The bomb, which killed Highways Minister Jeyaraj Fernandopulle, along with a former top marathon runner and the national athletics coach, as they were about to see off the runners in Weliweriya, also injured dozens of other athletes and onlookers.

"Such violence shows a complete disregard for the right to life and security of Sri Lankans, and breaches the most fundamental principles of international law", Arbour said.

The attack is alleged to have been committed by Liberation Tigers of Tamil Eelam (LTTE), which has been accused of other recent attacks, including bombings of public transport and in other public places.

"I remind the LTTE and other armed groups that attacks which directly or indiscriminately target civilians are crime under international law", the High Commissioner said, "Violent attacks on people taking no active part in hostilities are strictly prohibited." Such acts of violence also undermine efforts for a meaningful dialogue on improving the situation of the Tamil minority in Sri Lanka, she said.