BOGOTA – At least 22 FARC guerrillas were killed early Sunday in fighting with the National Police near San Miguel, a town in southern Colombia close to the border with Ecuador, where eight police officers died in a rebel ambush earlier this month, officials said.

The Revolutionary Armed Forces of Colombia, or FARC, guerrillas were killed in coordinated operation by the National Police with the support of the army and air force, Defense Minister Rodrigo Rivera said.

President Juan Manuel Santos, for his part, thanked Ecuadorian officials for their assistance with the operation.

“The cooperation of the government of Ecuador ... is very important, and I am going to personally call President (Rafael) Correa to thank him,” Santos said.

The deaths of the 22 guerrillas “is the biggest blow in recent times against” the FARC, the president said.

The bodies of the dead guerrillas were taken to the town of Puerto Asis, Rivera said.

“Very valuable cooperation from the officials in Ecuador,” the defense minister said.

Rivera and National Police director Gen. Oscar Naranjo visited the scene of the operation and the defense minister held a press conference on his return to Bogota.

The dead rebels belonged to the FARC’s 48th Front, Rivera said.

The operation took place on “Colombian territory” and involved Colombian police and army troops, Rivera said.

The fighting occurred near the San Miguel River in Putumayo province.

The FARC’s 48th Front attacked a police border post on Sept. 10, killing eight officers.

Santos, who before being inaugurated said he was open to talks with the country’s left-wig rebels, has continued the hardline policy of his predecessor, Álvaro Uribe, in dealing with the FARC.

The FARC have stepped up their attacks since Santos’ inauguration, killing 40 security officers so far this month in a series of rebel attacks that some analysts say are intended to force the government into peace talks.

“This shows the country, but above all those bandits, that our people are not under their control, but to the contrary, responding with incisiveness,” President Juan Manuel Santos said in a phone conversation with Rivera

The United Nations last Monday condemned the use by the guerrillas of gas cylinders to attack police in San Miguel, the placing of explosives on a fallen officer’s body and the planting of landmines as rebel forces withdrew, noting that the FARC’s actions could constitute “war crimes.”

The guerrillas have escalated their attacks this month, with 56 people killed and 52 others wounded in the violence, the U.N. said.

The FARC has expressed a willingness to start a dialogue with the government since President Juan Manuel Santos took office on Aug. 5.

Santos, however, said he would fight the FARC as long as the guerrilla group continued to engage in “terrorism,” adding that the rebels would have to stop staging kidnappings and release all hostages.

The FARC, Colombia’s oldest and largest leftist guerrilla group, was founded in 1964, has an estimated 8,000 fighters and operates across a large swath of this Andean nation.