Colombia's President Juan Manuel Santos has ordered the resumption of bombing raids against FARC rebels after an attack he blamed on the group killed 10 soldiers, a move that will intensify combat after efforts to ease tensions.

As part of peace talks with the Revolutionary Armed Forces of Colombia (FARC), Santos last month stopped air raids on rebel hideouts in recognition of a unilateral ceasefire declared in December by the group.

The soldiers were killed in rural southwestern Cauca province in the early hours of Wednesday when the FARC launched an ambush, hurling grenades and firing on them as they sheltered in a covered sports pitch, the army said.

"This incident was a product of a deliberate attack by the FARC, it was not a coincidence and this implies a clear rupture of the promise of a unilateral ceasefire," Santos said, after meeting with his defence team in the city of Cali.

"I have ordered the armed forces to lift the suspension of bombings on FARC camps."

Santos said the attack, which also killed a FARC fighter, would not go unpunished. At least nine government troops were confirmed injured.

But FARC commander Pablo Catatumbo said the rebel fighters had only defended themselves, in line with the guerrillas' ceasefire announcement last December.

"There was a military confrontation caused by an army seige, which is not new. This operation against these units has been going on for four months," Catatumbo told a press conference in Cuba, where peace talks are being held.

Catatumbo, who led the guerrilla units involved in the clash before joining the FARC negotiating team in Havana, called on Santos to reverse his decision to renew air strikes.

"The solution is not to start bombing again. Please, they've been bombing in Colombia since the war began and it's only accomplished one thing, to increase the number of dead," he said.

The government has refused to commit to a bilateral ceasefire until there is a final peace deal.

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Deadliest attack since ceasefire

Al Jazeera's Alessandro Rampietti, reporting from the Colombian capital Bogota, said: "This is the deadliest attack since they [rebels] announced the unilateral indefinite ceasefire back in December. And it comes just a few days since the Colombian government announced the extension of the suspension of the air raids over FARC camps.

"At this point it is not clear what kind of consequences [the attack] will have on the peace talks."

FARC negotiators committed to a unilateral ceasefire to promote peace talks that have taken place in Cuba over the past two years, saying they would only fire weapons if attacked by the armed forces.

In a good faith gesture, the government responded by suspending all aerial attacks on guerrilla camps, a move that Santos reaffirmed this week.

But it is unclear how much control the leadership in Havana has over all of FARC's estimated 7,000 troops on the battlefield, especially in turbulent, lawless areas like Cauca, where rebel commanders are known to be heavily involved in drug-trafficking.

Source: Al Jazeera and agencies