Colombia's FARC rebel leader Rodrigo Londono, known by his nom de guerre Timochenko, was hospitalised after suffering a stroke and is expected to recover, doctors said on Sunday.
Timochenko, who in November signed a peace agreement with the government, suffers from heart problems and had surgery in Cuba while negotiating the accord.
Last week the leader oversaw the disarmament of his 7,000 or so rebels at a ceremony with President Juan Manuel Santos.
Timochenko, who doctors say is 59 years old, suffered an ischemic stroke, a cerebrovascular accident caused by a blockage that deprives part of the brain from receiving blood and oxygen.
He is expected to leave the hospital within 48 hours and doctors told reporters Timochenko is chatting with them and even making jokes.
The FARC, which was founded as a peasant rebellion in 1964, has fought more than a dozen governments in a war that has killed more than 220,000 and displaced millions.