South Korea paid the Taliban $950,000 -- or $50,000 a head -- to secure the release of 19 church workers abducted in southeastern Afghanistan, Afghan officials who took part in the negotiations told ABC News.
The negotiations took on urgency, the Afghan officials said, after two female hostages who were released last month reported being repeatedly raped by their Taliban captors.
The kidnappers also killed two of the male hostages, who were abducted six weeks ago riding by bus through southeastern Ghazni province.
"We have reports the various Taliban commanders were fighting over the women hostages," said Mirajuddin Pathan, the governor of Ghazni province. "They were abused over and over."
South Korean Foreign Minister Song Min-soon today defended the decision to negotiate with the Taliban, according to The Associated Press. The move raised concern it would lead to more abductions and put thousands of foreign troops and aid workers at risk.
Seoul has insisted no ransom was paid.
But an Afghan official who took part in the negotiations, and who asked not to be named, said a cash pay-off was always central to their release.
"The Taliban initially asked for a million dollars a head, and for some prisoners to be released," he said. "When they realized time was not on their side, they dropped their price and their demand for prisoners."
The former hostages left Afghanistan on a chartered United Nations flight today to Dubai, in the United Arab Emirates. They were due to arrive in Korea early on Sunday.
The missionaries told of being separated into small groups, moved frequently and at night to avoid detection over the six weeks they were in captivity.
"Over the 42 days, we were relocated 12 times," AP Television quoted 55-year-old Yoo Kyung-sik as saying. "They moved us mainly during the night by motorcycle, turning off their headlights while to avoid being seen."
The freed hostages apologized for the grief they caused their families and their nation.
"We caused so much anxiety," Suh Myung-hwa told AP Television. "I feel really sorry and grateful to the people of my country."
In March, Taliban forces in southern Helmand province kidnapped Italian journalist Daniele Mastrogiacomo along with his Afghan driver and translator.
Mastrogiacomo was released unharmed after the Italian government pressured Afghan President Hamid Karzai to release five key Taliban prisoners. Mastrogiacomo's driver and translator were beheaded.
Last week, a German aid worker was abducted in broad daylight from a restaurant in the capital Kabul. She was later rescued in a police operation.
Another German aide who was abducted last month by the Taliban appeared in a TV video this week pleading for his government to negotiate for his release. So far, the German government has refused.
ABC News' Aleem Agha reported this story from Kabul, Afghanistan, and Gretchen Peters from Islamabad, Pakistan.