Eight people, including six police, were killed and 90 others injured in a bomb explosion when a suicide bomber drove a motorbike into a bus carrying police personnel in central Colombo, reported the Ministry of Defence.
The explosion went off near a security checkpoint on the road leading to the president's office within a high security zone at noon (0630 GMT), army spokesman Brigadier Udaya Nanayakkara said, reported dpa.
Two of those killed and many of the injured were civilians, said the defence ministry.
Dr Hector Weerasinghe, director general of National Hospital, said that more than 90 people have been already admitted to the hospital.
Initial reports said that a three-wheeler packed with explosives had rammed a police bus which was parked on the road.
The Ministry of Defence claimed the Liberation Tigers of Tamil Eelam (LTTE) rebels were responsible for the attack.
The incident came less than four hours before the newly-elected chief minister for the eastern province was to be sworn in. The military had ousted Tamil rebels in military operations earlier this year and provincial elections were held there Saturday.
Similar military operations are in progress in the northern province to recapture rebel-held areas.