The National Times - Colombia suspends truce with major rebel group in flashpoint regions

Petro said the bilateral ceasefire "is suspended and all offensive operations are reactivated" in the Meta, Caqueta, Guaviare and Putumayo regions.

Four children and teenagers from the Murui Indigenous community were executed in southern Colombia by dissidents of the now- disarmed Revolutionary Armed Forces of Colombia (FARC) rebels, authorities said on Sunday.

Those four regions are a stronghold of FARC dissident guerrillas who refused to join a 2016 peace accord that saw most of the rebels lay down their arms and form a communist political party.

The rebel Estado Mayor Central responded to the news with a scathing attack on the government.

"The unilateral ceasefire will unleash war and the numbers of dead, injured and prisoners will multiply," the group said in a statement sent to media.

The four Murui minors were executed on the border between the southern departments of Caqueta and Amazonas after defecting from a dissident faction of FARC called the Carolina Ramirez front, the country's human rights ombudsman said in statement on Sunday.

The front, which belongs to the Estado Mayor Central, was among the groups that adhered to a ceasefire proposed by the government several months ago and were set to begin new peace talks soon.

"Recruiting and killing children and adolescents from Indigenous communities are not exactly gestures of goodwill to achieve peace. In addition to being evident violations of international humanitarian law," the ombudsman noted.

Petro slammed the murders as "an atrocious crime, a blow to peace" and warned of "measures against these actions."

- Government under fire for negotiating -

At the end of last year, Petro announced a bilateral ceasefire with numerous armed groups.

But three of those truces have now ended following the breakdown of the peace process with the National Liberation Army guerrillas and the Gulf Clan drug traffickers.

"If the ceasefire is not effective in certain territories in protecting the lives and integrity of the population, then there is no sense in persisting with it," Petro wrote on Twitter.

Since coming to power last year, Petro has tried to negotiate peace with the country's various armed groups in a marked shift from his conservative predecessor's more bellicose approach to resolving the conflict.

This policy has triggered a hailstorm of criticism of Petro. The opposition has branded the armed forces too weak to prevent armed groups dictating the terms of peace.

In its statement, the Estado Mayor Central accused the government of failing to install the necessary mechanisms to verify that the ceasefire was being respected.

Colombia has suffered six decades of armed conflict between the state and various groups of left-wing guerrillas, right-wing paramilitaries and drug traffickers.

Petro, the first leftist president in Colombia's history, has opened talks with many of the armed groups, hoping to put an end to the violence in the world's largest cocaine producer.

S.Mitchell--TNT