The Revolutionary Armed Forces of Colombia (FARC) have set free a second hostage in a week with the release on Thursday of regional deputy Sigifredo López, who was kidnapped by the guerrilla group in 2002.
The news comes days after former governor Alan Jara was released. Last week, the FARC also released three police officers and a soldier.
The latest releases were facilitated by the International Committee of the Red Cross (ICRC), the Brazilian government and Colombian congresswoman Piedad Córdoba. They are the latest in a series of releases of high-profile hostages over the last year.
Amnesty International has reiterated that hostage-taking is a serious violation of international humanitarian law, which can constitute a war crime.
"The release of the hostages, the police officers and the soldier is great news but the reality is that there are still many being held by the FARC and the ELN across Colombia," said Marcelo Pollack, Colombia researcher at Amnesty International. "Both guerrilla groups must urgently and unconditionally release all those civilians still being held captive."
Over the last few years, there has been constant speculation that the FARC and the Colombian government were prepared to agree a "humanitarian exchange" - the exchange of FARC prisoners held by the Colombian authorities for hostages held by the guerrilla group.