Colombian troops killed 36 FARC rebels in gunbattles, military officials said Wednesday, but mediators announced that the guerrillas will begin a frequently delayed release of hostages within days.


The country’s defense chief Juan Carlos Pinzon told reporters that the rout of the rebels in the joint air force and army operation overnight was “without a doubt one of the hardest strikes of the past five years” against the FARC.


The main operation killed 33 insurgents in Arauca province, the same eastern area bordering Venezuela where rebels with the the Revolutionary Armed Forces of Colombia ambushed an army unit over the weekend, killing 11 soldiers.


Officials said three other rebels were killed on Tuesday in Arauca during firefights with the army and four more were captured.


President Juan Manuel Santos in a Twitter message hailed the “huge blow against the FARC in Arauca where they killed our soldiers,” but reiterated that the nation needed peace to prevail.


The violence followed FARC overtures — thus far deemed insufficient by the government — to make peace with Bogota.


The FARC, Latin America’s last major insurgency, said through the mediator that it plans to start releasing 10 military hostages on March 26, under a pledge announced last month.


The rebel group announced in February but later stalled on a plan under which the six police and four soldiers it still holds would be released, and would end the practice of kidnapping for ransom.


The FARC has continued, however, to be active in clashes with army forces.


Santos has said he would open a direct dialogue with the leftist rebels only when all hostages are released and the group vows to cease “terrorist” actions. He also wants the FARC to stop recruiting children.


The FARC, believed to have 8,000 members, has been at war with the government since 1964. It began a campaign of kidnappings in the mid-1980s, seizing army hostages to serve as bargaining chips for FARC prisoners.


Defense chief Pinzon again called for the rebels to demobilize, arguing that it made no sense for the FARC to continue their armed struggle.


In November, Colombia’s military killed FARC leader Alfonso Cano, whose real name was Guillermo Leon Saenz Vargas, in a day-long gunfight that was hailed as the biggest blow in years to the insurgents.


The rebels quickly replaced Cano with Timoleon Jimenez, alias Timochenko, but they shrugged off the government’s overture for peace talks at the time.