A bomb was 'planted' in a van outside a Tamil newspaper office
A bomb in a parked van outside a newspaper office of a Tamil political party in the Wellawatte area went off before the morning rush hour.
The newspaper office is run by the Eelam People's Democratic Party (EPDP), an ally of the Sri Lankan government and opposed to the Tamil Tiger rebels.
No-one has yes said they carried out the explosion.
Windows of neighbouring buildings were shattered by the blast, according to reports.
'Traitors'
Senior police official Sarath Lugoda told the Associated Press news agency the bomb was planted in a van belonging to the EPDP and parked outside the party's newspaper office.
"It is too early to put a blame, but our investigators are on the job," military spokesman Brig Nalin Witharange said.
The EPDP is one of several former militant groups now allied with the government - a move which has pitted them against the Tamil Tigers, who consider them to be traitors.
Party leader, Douglas Devananda, has survived a number of attempts on his life, allegedly by the rebels.
Officials in Sri Lanka have confirmed that an explosion, which occurred during morning rush hour in Colombo, injured one person. The explosion occurred outside a newspaper office of a political party allied with the Sri Lankan government.

There have not been any claims of responsibility yet, although a senior police officer has said that the bomb was planted in a van belonging to the political party, which used to be a militant group against the government.