( AP ) - Amnesty International said it appealed for the release of 21 South Korea hostages during a phone conversation with the Taliban, warning the militants that holding and killing captives was a war crime.
The London-based human rights group said it spoke with a purported Taliban spokesman, Qari Yousef Ahmadi, on Thursday.
"Hostage taking and the killing of hostages are war crimes and their perpetrators must be brought to justice," Irene Khan, Amnesty secretary-general said in a statement.
Ahmadi told Amnesty that "we are trying to resolve this issue ... acceptably," but did not agree to protect the hostages from harm or release them immediately, the statement said.
There was no immediate comment from the Taliban on the conversation.
The Taliban have shot and killed two men in the group, which was doing voluntary health work in Afghanistan. They were abducted on July 19 in Ghazni province as they traveled by bus from Kabul to Kandahar.
The Taliban have demand the release of militant prisoners in exchange for the remaining hostages - 16 women and five men. Afghanistan has rejected that demand, but South Korea has urged both the U.S. and Afghan government to exercise "flexibility" in handling the crisis.
South Korea expressed hope Friday that a summit this weekend between President Bush and Afghan President Hamid Karzai would advance efforts to win the release of the hostages.
"We have expectations that the two leaders would have sufficient understanding of our position when they hold a summit," said South Korean presidential spokesman Cheon Ho-sun.
South Korean lawmakers were also in Washington to appeal for U.S. help in the standoff.
Richard Boucher, assistant U.S. secretary of state for South and Central Asia, said the use of military force to free the hostages had not been ruled out.
"All pressures need to be applied to the Taliban to get them to release these hostages," Boucher said Thursday. "There are things that we say, things that others say, things that are done and said within Afghan society, as well as potential military pressures."
Afghan officials said the Taliban captors have agreed to meet with South Korea's ambassador to Afghanistan, but they had not yet agreed on a venue.
"If the Taliban want to come to the area where we are for the sake of these hostages, 100 percent, they will be safe," Ghazni Gov. Marajudin Pathan told a news conference Thursday.
Both sides have proposed places that could put the other at risk, including the office of the provincial reconstruction team, which is run by U.S. troops serving with NATO-led force.
"The Koreans told the Taliban to come to the PRT, and the Taliban told the Koreans to come to their base," Pathan later told The Associated Press.
A group of local doctors, meanwhile, traveled from Kabul to Ghazni in hopes of reaching the hostages and treating those in a need of medical care.
Ahmadi said Thursday that the remaining 21 hostages were still alive, but that two of the women were sick and could die.