Colombia's Marxist FARC rebels have suspended a unilateral ceasefire after government troops killed 26 of its fighters.

The Revolutionary Armed Forces of Colombia, or FARC, said on Friday it lifted the ceasefire because of the attack, one of the deadliest confrontations since the two sides began negotiations in Cuba at the end of 2012.

The group slammed Colombian President Juan Manuel Santos for "incoherence" in seeking peace while his military continued attacks against FARC encampments.The rebel ceasefire had been in place since late December.

"The suspension of the unilateral ceasefire was not in our sights...the incoherence of Santos's government has achieved it," the FARC said in an statement on its website.

However, rebel negotiator and member of the group's seven-member secretariat, Pablo Catatumbo, told the Reuters news agency in Havana that dialogue would continue.

"There is a tense atmosphere that has tarnished the talks these days."

'Spiral of violence'

The FARC statement repeated the group's demand that the government also declare a ceasefire "for the health" of the process and to prevent further casualties, but Santos has refused to halt offensives until peace is signed.

Minutes before the rebel statement, Santos urged the group in a televised address to accelerate the pace of talks. He encouraged an end to the "spiral of violence, hate and vengeance" and praised the armed forces for their efforts.

The bombing raid and ground combat that killed the 26 at their jungle camp took place in the key drug trafficking region of Cauca where the FARC has a strong presence.

"The rebels will be thinking about retaliation," Santos said, standing beside his military leadership in Bogota.

"What we have to do is stop; stop and transform it into a spiral of forgiveness and reconciliation."

Peace talks to halt a conflict that has killed more than 220,000 people and displaced millions have so far resulted in partial agreement on three items on a five-point agenda.

The rebel deaths come a month after the FARC killed 11 soldiers in the same region, prompting the government to restart bombing raids on guerrilla camps after a brief suspension.

At the time, the FARC called the incident a legitimate case of self-defense in reaction to an offensive by government troops.

Source: Agencies