Colombia's military has killed 36 rebels in an air strike on a guerrilla camp, striking a second blow in less than a week to the country's main guerrilla force.

The attack in the Meta state municipality of Vista Hermosa, a traditional stronghold of the Revolutionary Armed Forces of Colombia (Farc), comes as the group says it is preparing to free its last prisoners.

Colombia's armed forces chief, General Alejandro Navas, dismissed suggestions that the military attacks could delay the releases, saying the strikes fell within the "rules of the conflict". He said Monday's raid had been planned for several months.

Navas said the rebels were undergoing training in an area where the Andes ridge meets Colombia's south-eastern plains that is the base for the Bloque Oriental, the Farc's most potent cadre.

Commandos captured five insurgents, including three women, and seized weapons and computers, the military high command said.

President Juan Manuel Santos said three rebels were wounded.

"This operation isn't over," Navas said, emphasising what he called its "highly strategic" nature.

Last week the military killed 33 rebels in a similar air raid on another Farc stronghold in Arauca state, near the border with Venezuela.

Although Colombia's military leaders have not released many operational details, the attacks follow a new strategy devised after they tracked down and killed the Farc's previous commander, Alfonso Cano, last year.

Santos said at the time that, given that the conflict was in what he called "its final phase", the military would go after the Farc's logistics and supplies.

The rebels took up arms in 1964, demanding a more equitable distribution of wealth in a country where land ownership is highly concentrated.

They have engaged the government in several failed attempts at peace, most recently in 1999-2002. During those talks, the Farc was afforded a Switzerland-sized safe haven that included Vista Hermosa and it continued operations elsewhere in Colombia.

The rebels have been increasingly battered over the past decade as Colombia professionalised its military with US assistance, and were seeking peace talks even before Cano was killed.

The Farc has said it plans to release its last prisoners, 10 soldiers and police officers held for as long as 14 years, on 2 and 4 April. It recently announced a halt to ransom kidnappings that have been a financing tool along with the cocaine trade.

Yet neither the insurgents, who have about 9,000 fighters, nor Colombia's armed forces have eased up on military operations.

The military's 21 March raid in Arauca came four days after rebels in the region killed 11 soldiers.

Military analyst Alfredo Rangel said the government's military offensive could prompt the Farc to delay the prisoner releases. Doing so, however, would badly "hurt its image before the nation and international community", he said.

An activist who has long worked for the freedom of security force members held by the Farc, and who is expected to receive the 10 captives, expressed optimism on Monday.

Marleny Orjuela said: "I don't think that because of these operations the releases will be cancelled."