Betancourt, 46, who holds dual French-Colombian citizenship, had been the focus of an international campaign since her capture in 2002 by the Revolutionary Armed Forces of Colombia, known as FARC, with leaders including the French president attempting to negotiate her release.
"The release of the 15 hostages for a high ransom was first negotiated, and after that a rescue operation was staged," Radio Suisse Romande reported, citing an anonymous source.
According to official reports, Betancourt, the three U.S. citizens and 11 Colombians were freed from captivity Wednesday after undercover Colombian military intelligence officers infiltrated the FARC command structure and convinced the local commander that they were taking the hostages by helicopter to FARC's leader Alfonso Cano.
After landing near a military base in Guaviare, the helicopter was surrounded by military commandos and the rebels on board surrendered without putting up armed resistance.
Colombian President Alvaro Uribe, whose father was killed by FARC insurgents, and who has consistently refused to make any compromises with the group, said: "This was an intelligence operation comparable with the greatest epics of human history, but without a drop of blood being spilled, without one weapon being fired."
Swiss media reported that the staged "rescue operation" allowed Columbian President Alvaro Uribe to improve his political image in the country after his authority had been seriously undermined by allegations that his re-election was a result of a rigged campaign.
The French government earlier said no ransom had been negotiated with the Colombian rebels.
Russia's Foreign Ministry hailed Friday the swift and bloodless operation to free the 15 hostages and urged the Colombian rebels to release all hostages still in captivity.
"We call for the immediate release of all hostages kept by the rebels and a quick and peaceful resolution of the internal conflict in Colombia," the ministry said in a statement.
The rebel group still has at least 800 hostages, including 30 politicians, servicemen and police officers, who they hope to exchange for 500 FARC members held in Colombian prisons.
FARC has been fighting against the Colombian authorities since 1964 and is accused by the West of terrorism and drug-trafficking. The U.S. and the European Union have put the FARC on the list of international terrorist organizations.