Afghan authorities have found the body of the South Korean hostage who was killed by the Taliban on Monday.
The discovery comes amid threats from the hard-line Islamic militants that more of the 21 remaining captives will be executed if their demands are not met. Another of the hostages was killed last week.
The militants have set Wednesday as the latest deadline for their demands -- primarily the release of an equal number of Taliban prisoners in exchange for the hostages -- to be met.
"They've made good on two previous threats and so they're now sort of toying with the idea, oh, we might just do one, it might be a woman, it might be a woman and a man or maybe we'll just execute all of them, and that certainly increases the sense of urgency and pressure to do something," said CTV's Denelle Balfour, reporting from Kandahar.
Meanwhile, Seoul called on the international community to take action, even if it meant breaking the established policy of refusing to give in to the demands of hostage-takers.
"The (South Korean) government is well aware of how the international community deals with these kinds of abduction cases," said an official statement.
"But it also believes that it would be worthwhile to use flexibility in the cause of saving the precious lives of those still in captivity and is appealing (to) the international community to do so."
President Hamid Karzai took criticism in March for approving an exchange of Taliban fighters for Italian reporter Daniele Mastrogiacomo. He called it a one-time deal and has made no indication that he is considering another trade.
The body of Shim Sung-min, 29, a former information technology worker who was volunteering with the Christian group, was found Tuesday on a road in the village of Arizo Kalley about seven kilometres west of Ghazni city.
He was reportedly shot in the head.
Shim was making preparations to attend graduate school. He had served as an army officer and had spent five days doing volunteer work in the Philippines, The Associated Press reports.
He is the second of the original 23 hostages to be killed. The first, the pastor leading the group, Bae Hyung-kyu, was killed last week, though the circumstances surrounding his death are still unclear.
The Koreans were taken hostage on July 19 when the bus they were travelling on from Kabul to Kandahar was boarded by the militants in Ghazni province.
Qari Yousef Ahmadi, a purported Taliban spokesperson, said Sung-min was killed because authorities have not yet met the group's demands, despite the passing of several previous deadlines.
"The Kabul and Korean governments are lying and cheating. They did not meet their promise of releasing Taliban prisoners," Ahmadi said by phone from an undisclosed location.
Ahmadi warned that the new deadline expires at noon Wednesday, at which point the militants will begin killing more hostages.
"It might be a man or a woman ... It might be one. It might be two, four. It might be all of them," he said.
Meanwhile the Al-Jazeera television network released footage of what it said were a number of South Korean hostages.
In the shaky video, seven of the female captives were seen crouching in the dark silently with their eyes closed or staring at the ground, and revealing little emotion by their expressions.
The authenticity of the video could not be immediately verified and the network did not explain how it obtained the footage.
Afghan clerics and political leaders have called the hostage-taking of women un-Islamic, saying it contradicts Afghanistan's culture of hospitality and will reflect badly on the country.
With files from The Associated Press
