Colombo - One police officer was killed and 12 other people including four schoolchildren were injured when a bomb affixed to a bicycle exploded in an eastern town of Sri Lanka on Tuesday morning, a police spokesman said.

The bicycle was parked close to the main police station in Batticaloa, 240 kilometres east of the capital and a remote- controlled device was used to detonate the bomb, he said.

Police said they believe that rebels of the Liberation Tigers of Tamil Eelam were responsible for the explosion.

The eastern part of Sri Lanka was secured from Tamil rebels in 2007, but sporadic incidents have been taking place in the area.

Government troops are carrying out operations in the northern part of the country and have encircled the rebel stronghold located in the Mullaitivu district, 385 kilometres north east of the capital. (dpa)