In a video recorded by British journalist Karl Penhaul and released Sunday, the organization, also known as FARC, said Langlois had a slight arm injury but was doing well, Colombia Reports said Monday.
Langlois was injured during a confrontation between FARC and government forces, the report said.
A FARC commander identified as Ancizar said in a statement guerillas killed 17 soldiers in the clash. Government reports indicated four soldiers were killed.
Ancizar said FARC learned of Langlois' identity as a journalist through the media and was hoping for a quick "solution to the impasse."
Langlois disappeared April 28 while reporting on anti-narcotics operations in Caqueta.