Ecuadorean authorities say a guerrilla faction that was once linked to Colombia's largest rebel group is responsible for an attack that left three soldiers dead.

Gov. Pablo Hadathy Rodas of the northwestern Esmeraldas province where Tuesday's attack took place told a Colombian radio station that the rebels are now involved in drug trafficking and were behind a recent spate of violence along the border.

He told BLU Radio the guerrilla faction operates in a remote part of Colombia where the state has little or no presence.

Government officials have said they estimate there are about 1,000 rebels who now pertain to groups which did not take part in Colombia's historic peace accord.

President Lenin Moreno said he is sending 12,000 troops to boost security along the border.