Bogota  - Eight Colombian police officers were killed Friday in a bomb attack by leftist rebels on a road in the northeastern province of Arauca, on the border with Venezuela, officials said.

Nobody immediately claimed responsibility for the attack, although both the Revolutionary Armed Forces of Colombia (FARC) and the smaller National Liberation Army
(ELN) - both leftist groups - are active in Arauca.

The attackers allegedly killed off those who survived the initial bombing.

"The patrol was attacked with bombs by a guerrilla group that remains unidentified so far, and then they were shot with firearms," the mayor of the town of Fortul, Jorge Munoz, told Caracol Radio.

Munoz noted that the officers were headed for the cemetery in Fortul, because the rebels called them saying that a dead body had been found in order to ambush them.

The alleged rebels planted explosives that they detonated as the police vehicle drove by, killing eight officers and injuring another.

Colombian Defence Minister Juan Manuel Santos offered a reward to anyone providing information that might lead to the arrest of those who ambushed the police officers.

Colombia has been plagued for over 40 years by a bloody armed conflict between rebels and the central government, in which ideological issues mix with others linked to the lucrative drug trade. (dpa)