BOGOTA - Five police officers have been killed and three injured by a roadside bomb in the Colombian state of Caqueta, acting Governor Edilberto Endo said.

The policemen were driving along a highway when a bomb exploded and set their car on fire.

Mr Endo blamed the attack on the Farc rebel group.

If confirmed as having been carried out by the rebels it would be the worst Farc attack since President Juan Manuel Santos came to power last month.

The Farc, Colombia's largest left-wing rebel group, has been putting up fierce resistance against an offensive by government troops in Caqueta.

Farc leaders issued a call for dialogue before Mr Santos was inaugurated.

However, Mr Santos has said that he is only prepared to talk to the rebels if they lay down arms and release all of the hostages that they hold.