"They say they have made their demands clear to government and think they're playing for time."
The Afghan government said earlier on Sunday that it wanted the 16 women in the group of Christian aid workers abducted 10 days ago to be freed before it would consider any Taliban demands.
But one of the leading members of the negotiating team said that a release of prisoners was not up for discussion.
The official line from Kabul, from the interior ministry and presidential palace, is that a hostage swap is not something they will contemplate.
An Afghan team that was supposed to have held more talks with the Taliban on Saturday could not reach the group because of security concerns in Ghazni province, a provincial source said.
The team hoped to persuade the group to free the Christian volunteers without condition.
Qari Mohammad Yousuf, a Taliban spokesman, told Al Jazeera his group's demands have not changed.
He said: "We have the same previous demands; the first is accepting to withdraw the Korean forces from Afghanistan."
"The second demand is still pending as the Afghan government delegation has said that it does not have the authority to release Taliban prisoners."
All of the hostages are in bad health, Yousuf said on Saturday.
"If anything happens to them, the Afghan government and the South Korean government will be responsible."
The South Koreans were seized while travelling on the highway between Kabul and Kandahar on July 19 in Ghazni province, about 140km south of Kabul.
|Baek met Karzai in an attempt to |
speed up the negotiations [AFP]
The aid mission was reportedly in the country to provide free medical services.
The Taliban has also demanded that Seoul withdraw its 200 troops serving with US-led multinational forces in Afghanistan.
South Korea responded by saying it would pull them out as previously scheduled by the end of the year.
Earlier in the day, Hamid Karzai, the Afghan president, met Baek Jong-chun, South Korea's presidential envoy, to discuss the fate of the hostages.
Baek, chief presidential secretary for foreign and security affairs, was dispatched to Afghanistan after the Taliban shot dead the leader of the group, a 42-year-old pastor whose body was found on Wednesday.
Source: Al Jazeera and agencies