Leftist rebels with the National Liberation Army (ELN) claimed responsibility Saturday for this week's attack on a Colombian army helicopter in which eight troops were killed.

The incident took place on Monday, in the northern department of Norte de Santander.

"On June 22. ... at 12:30 pm, in ... Teorama, Norte de Santander, ELN units down Black Hawk with the plates EJC-185," the rebels said in a statement released online.

The army had reported the attack Monday but blamed the Revolutionary Armed Forces of Colombia (FARC).

Fighting in Colombia has intensified in recent weeks since the unravelling of a unilateral ceasefire declared by the FARC, which had been hailed as a sign of progress in the peace talks the FARC have been holding with the government since November 2012.

But the ELN, a smaller force, has held exploratory talks on a peace process. So far, progress has not been made.

The Colombian conflict has killed more than 200,000 people and uprooted more than six million since the FARC was founded in 1964.

The FARC has some 8,000 fighters mostly in rural areas; the ELN has about 2,500.