Bogota, February 2 (RHC)-- The peace process between the Colombian government and the country's second largest rebel army, the ELN, received a major boost Thursday as the rebels released a high-profile hostage, fulfilling the government's central precondition for advancing formal end of conflict negotiations that have stalled for months. 

The National Liberation Army, known as ELN, handed over former member of Congress Odin Sanchez to a humanitarian commission of the Red Cross, the mediator in the release, near the Baudo River in the department of Choco. 

"The humanitarian commission of the ELN kept its word of delivering Mr. Odin," the official radio of the ELN, Ranpal, wrote on its Twitter account. 

Earlier Thursday morning, Sanchez told Colombia's W Radio that he was boarding a helicopter en route to his release.  After the exchange between the ELN and the Red Cross, Sanchez was transported in another helicopter to Quibdo, where he was set to meet his family. 

Meanwhile, a second operation was also launched Thursday morning for the government to deliver two pardoned ELN members to the rebel group. 

"We await with great care and joy the release of our pardoned comrades who are in poor health," the ELN peace delegation wrote on its Twitter account, along with updates reporting that the operation to hand over the two ELN members was in process. 

The rebel army demanded that the government pardon two ELN prisoners in exchange for Sanchez' release.  The prisoner exchange has been the main pending issue that has kept peace negotiations between the two sides of the more than five decade-old conflict from moving forward. 

Talks were initially scheduled to begin on October 27 in Ecuador's capital of Quito, but the government called off the event in a surprise move just hours before it was set to begin, citing the ELN's failure to release Sanchez as the reason for the postponement.  Disagreement over the timeline for Sanchez' release revealed differing interpretations of preliminary agreements that laid the foundation for formal talks. 

President Juan Manuel Santos has repeatedly said that the negotiations cannot move forward before Sanchez' release, but the ELN pressed authorities to also pardon two rebels as a show of goodwill to advance the process.