Colombo  - At least 12 policemen were killed and 20 others were injured when a Tamil rebel suicide bomber set off an explosion outside the office of a senior police officer on Monday morning, military spokesman Brigadier Udaya Nanayakkara said.

The bomber set off the explosion in the Vavuniya town, 240 kilometres north of the capital.

The town is an area fully controlled by the security forces. (dpa)