However, the kidnappings underscored the threat that Farc fighters and other armed opposition groups are still active in remote, rural areas.

The Farc has been battered and weakened by government forces and foreign investment, especially in oil and mining, has grown rapidly.

Colombia is Latin America's fourth largest oil producer with output of more than 700,000 barrels per day.

Armed group fighters, who are holding at least 24 soldiers and police for political leverage, have often kidnapped civilians for extortion.

The Farc plans to free two soldiers to the Red Cross next week.