Colombia's government and the FARC rebel group will resume peace talks on Tuesday, officials said, even though the country's presidential election has placed the process in doubt.

A source in the FARC delegation told AFP the talks would continue for about two days, instead of the 11 days that past rounds have typically lasted.

It would be their first session since Colombian President Juan Manuel Santos placed second to a fierce opponent of the peace talks, Oscar Ivan Zuluaga, in the first round presidential vote May 25.

Polls show the two neck-and-neck as they head toward a June 15 runoff.

Meanwhile in Bogota, the army reported that six FARC guerrillas were killed and seven others captured various operations in southwestern Colombia.

With an estimated 7,000 to 8,000 fighters, the FARC is the largest of two leftist guerrilla groups active in Colombia.

Zuluaga has placed tough pre-conditions for continuing peace talks if he is elected: a permanent cease-fire by the FARC and jail time for its leaders.

Santos, who has made the bid to end Latin America's longest insurgency the centerpiece of his presidency, has warned that Zuluaga's demands are non-starters that would prolong the 50-year-old conflict.

The Havana talks began in November 2012 and have led to partial agreements on terms for the FARC's political reintegration, rural development and drug trafficking.

But at least three major issues remain unresolved: the surrender of weapons, compensation for victims of the conflict, and whether a peace agreement would be ratified by a national referendum or some other means.