Colombia's leftist FARC rebels declared a unilateral two-month ceasefire Monday as they began talks in Cuba with the Bogota government on ending Latin America's longest-running insurgency.

But the government of President Juan Manuel Santos immediately made clear it would not be bound by the ceasefire and military operations against the FARC would continue.

The Colombian military is determined to "chase these individuals who have violated all types of laws ... and have attacked the lives and honor of Colombians," Defense Secretary Juan Carlos Pinzon said in Bogota.

Negotiators for the Santos administration and the Revolutionary Armed Forces of Colombia (FARC) were in Havana to resume negotiations formally launched last month in Norway, the first attempt at a negotiated peace in 10 years.

Ivan Marquez, the head of the FARC delegation, said the rebel ceasefire would take effect at 0500 GMT Tuesday and last through January 20.

"The leadership has ordered that all military operations against government forces come to a halt," Marquez said upon arrival at the talks venue.

He said that this was "another example of our desire to create a political environment conducive to the progress of the talks."

The rebel move was a "solid contribution to strengthening the climate of understanding needed for the parties starting talks to reach the result desired by all Colombians," Marquez said.

Colombian negotiators made no statement as they arrived at the convention center in the Cuban capital. Reporters were not allowed inside as the talks began.

Both Santos and chief government negotiator Humberto de la Calle have repeatedly said that government forces will maintain counter-insurgency operations during the peace talks with the FARC.

"There will be no military concessions, nor a ceasefire, nor demilitarized zones," de la Calle said before leaving Bogota on Sunday.

Both sides however have said they are confident that an end is near to the decades-long conflict that has claimed hundreds of thousands of lives is within reach.

De la Calle said Sunday that he believes this is "the defining moment" to reach a peace deal with the FARC, as both sides have agreed that talks "must end with a final agreement on the conflict."

This round of talks would likely last about 10 days, at which time a start date for the next round would be agreed.

The Santos administration wants to build "a stable peace," he told reporters as he boarded the plane for Havana, adding that "the FARC would be turned into a legal political party."

Negotiations to reach a final deal will likely last "months, not years," de la Calle said.

The FARC -- Latin America's largest rebel group, founded in 1964 and believed to have some 9,000 armed fighters -- took up arms almost 50 years ago to protest the concentration of land ownership in Colombia.

Little has changed over the years, as more than half of the country's largest properties are controlled by one percent of the population, according to a 2011 UN report.

There are however signs that the guerrillas may be ready for a truce after a long string of setbacks.

Several top commanders have been captured or killed in recent years as the group has suffered a string of military defeats and its ranks have dropped to half the number of fighters compared to the FARC's 1990s peak.

The talks, the fourth attempt at peace between the government and the FARC, will focus on a five-point agenda that includes the thorny issue of rural development.

Both sides must also agree on a mechanism to end hostilities, incorporate the rebels in political life, curb drug trafficking, and compensate victims of abuses committed by guerrillas and government troops.

According to the United Nations, hundreds of thousands of people have died and four million have been driven from their homes in the conflict, which also involves a smaller guerrilla army and right-wing paramilitary groups.