Colombia has suspended peace talks with the Farc rebel group after the apparent kidnapping of an army general.
Brig Gen Ruben Dario Alzate Mora was abducted by rebels in the northern province of Choco on Sunday, army officials said.
President Juan Manuel Santos demanded that his captors free Brig Gen Alzate "safe and sound".
The Farc and the government have been holding peace talks for two years but have not declared a ceasefire.
"Tomorrow negotiators were to travel to another round of talks in Havana," Reuters quoted President Santos as saying late on Sunday.
"I will tell them not to go and that the talks are suspended until these people are released."
Brig Gen Alzate was travelling along the Atrato river in the northern Choco province by boat.
He stopped at a village called Las Mercedes, about 15km (10 miles) from the provincial capital Quibdo to talk to the local community.
He was met there by rebels thought to belong to the 34th division of the Farc, reports say.
The rebels searched him and took him and two other people - lawyer Gloria Urrego and Corporal Jorge Rodriguez Contreras - captive, the army said.
President Santos said he had asked his defence minister to travel to Choco on Monday "to investigate Brig Gen Alzate's kidnapping".
Writing on Twitter, President Santos also demanded an explanation from the defence minister as to what Brig Gen Alzate was doing in an area of high rebel activity dressed in civilian clothes.
More than two years ago, the Farc announced they would stop their policy of kidnapping people in order to show their good will ahead of peace negotiations.
But after seizing two soldiers recently in eastern Arauca province they clarified that that policy applied only to civilians, not to military targets.
An estimated 220,000 people have died in five decades of armed conflict in Colombia.
President Santos was re-elected on a promise of driving the peace process forward, but Colombians are getting increasingly impatient with the slow pace of progress at the peace talks.