Move comes as FARC rebels declare two-month unilateral truce after holding meetings in Cuba with peace negotiators.

Colombia’s defence minister has issued a statement saying the country’s armed forces will not honour a ceasefire that FARC rebels unilaterally declared as peace talks opened in Havana.

Defence Minister Juan Carlos Pinzon was responding to the announcement of a unilateral ceasefire earlier on Monday by senior rebel negotiator Ivan Marquez.

Marquez declared a two-month ceasefire effective on Monday night, the first truce in more than a decade, as peace negotiators meet in Cuba in the latest attempt to end the five-decade-old conflict.

Pinzon said in a brief statement to reporters in Bogota that Colombia’s military had the “constitutional duty to pursue all criminals who have violated the Constitution”.

He said that as a result, what he called “the terrorists” of the Revolutionary Armed Forces of Colombia would be pursued “for all the crimes they have committed over so many years”.

‘Climate of understanding’

Marquez , FARC’s lead negotiator, said on Monday that the rebels would halt all attacks from midnight on Monday until 20 January.

He said it was “a contribution made to strengthen the climate of understanding necessary so that the parties that are starting the dialogue achieve the purpose desired by all Colombians”.

Revolutionary Armed Forces of Colombia, or FARC, said it would halt all offensive military operations and acts of sabotage against infrastructure beginning at midnight on Monday night and running till January 20.

Marquez said now was the time for the Colombian government to transform its policies.

Inside Story Americas –

Will Colombia peace talks end FARC control?

“2012 has been unfortunate for the Colombians who are suffering the consequences of these policies and it would be just if, at Christmas, the regime of Juan Manuel Santos and the ruling classes announce an end to the social war imposed by their reforms and laws of misery and hunger,” he said.

Santos’ government, however, has so far rejected any stoppage of military operations until a final peace deal was signed with FARC and even pledged to step up the offensive.

The gesture is a positive sign that the rebels are keen to push talks forward to a successful end, something that was thrown into doubt by long, drawn out speeches by its leadership calling for major changes to Colombia’s political system.

Delegations for the government and the FARC arrived in black luxury cars at Havana’s convention centre where they will meet almost daily until the talks end.

The complex is located in Havana’s plushest neighbourhood, filled with palatial houses that once belonged to the elite, virtually all of whom fled Cuba after the 1959 revolution.

Colombian government negotiators did not speak upon arrival.

The war has dragged on for nearly half a century, taking thousands of lives, displacing millions more and causing damage to infrastructure in Latin America’s longest running anti-government campaign.

Long history

Failure of the peace process would mean years more of fighting and further blight on the reputation of a country eager for more foreign investment and regional clout, yet which has been unable to resolve its most serious domestic problem.

The conflict began in 1964 when the FARC emerged as a communist agrarian movement intent on overturning Colombia’s long history of social inequality.

The group has been weakened by a US-backed military offensive which started in 2002 and has reduced its numbers to about 8,000 and forced them into remote mountain and jungle hideouts.

But it still has the strength to launch attacks that Santos wants ended so the country can grow its economy, boosted in recent years by fast-growing oil and mining sectors.

The FARC has sustained itself by cocaine trafficking, kidnapping, ransom and “war taxes” charged within the territories it controls.

Its leaders deny involvement in the drug trade and renounced kidnappings earlier this year, but the US and European Union consider it a terrorist organisation.