Two soldiers were killed Sunday in an attack the Colombian army has blamed on guerrillas with the National Liberation Army (ELN).

The soldiers, who were on a motorcycle patrol in Arauca, in eastern Colombia on the border with Venezuela, were gunned down by "terrorists of the ELN" traveling in a vehicle, the army said in a statement.

Reinforcements were rushed to the area to search for the culprits, the statement added.

The ELN is Colombia's second-largest rebel group after the Revolutionary Armed Forces of Colombia (FARC).

President Juan Manuel Santos and the FARC signed a peace accord on November 24 to end five decades of warfare, after a first agreement was unexpectedly rejected by Colombians an October 2 referendum.

The ELN and the government began secret talks in January 2014 to pave the way for official peace talks, but the process has stumbled over the issue of hostages and prisoners.

The Colombian government has suspended the preparatory talks until January 10, insisting that the ELN first release hostage ex-congressman Odin Sanchez.

The ELN in turn called for the simultaneous release of two imprisoned rebels.

More than 260,000 people have died in Colombia's decades-long conflict, which drew in other guerrilla forces, right-wing paramilitary groups, drug traffickers and government troops.