* Peace talks set to resume in Cuba this week
* Deadliest attack against rebels since peace process began
* Santos says talks must not last past November 2013
By Luis Jaime Acosta
BOGOTA, Dec 3 (Reuters) - Colombian forces have killed at least 20 Marxist FARC guerrillas in an air and ground raid near the border with Ecuador, an army general said on Monday, the deadliest strike against rebels since a peace process started.
Despite talks to end 50 years of war, Colombia's government has vowed to keep up military operations even while the Revolutionary Armed Forces of Colombia, or FARC, called a two-month ceasefire as the two sides try to hash out a deal.
Colombian President Juan Manuel Santos is hoping a decade of U.S.-backed blows against the FARC has left the group sufficiently weakened to seek an end to the war.
In the most deadly attack since the two warring sides started negotiations in mid-October, an airstrike followed by a ground assault on three FARC camps in the southwestern Narino department killed at least 20 rebels late on Sunday.
"On the strength of the attack we found human remains that are in the process of being identified. We're talking about more than 20 dead, but the figure could be higher," General Leonardo Barrero, head of the Joint Command Southwest, told Reuters.
Barrero said that security forces have so far been able to identify six of the bodies.
Narino is a microcosm for a range of problems facing Colombia - weak government presence, drug production, poverty, and the presence of guerrillas and new criminal gangs that sometimes fight, sometimes become allies.
Peace talks, which are taking place in Cuba, are trying to tackle some of the root causes of the conflict such as agrarian development, drugs, political participation of opposition groups and victims' reparations.
Santos said at the weekend that the discussions should not drag on for too long and said they must be completed by November next year or earlier. The rebels have said they would remain at in negotiations as long as necessary.
After a short break from the first round of discussions in Havana about rural development, negotiating teams are expected to resume talks this week.
Both sides have said negotiations were going as expected.
"Last night I met with my negotiating team. The balance of the first meeting was positive. No one is thinking about modifying timeliness. Months, not years," Santos said on Monday in a message to his 1.4 million Twitter followers.
(Additional reporting by Jack Kimball; Editing by Jackie Frank)