Afghan elders on Friday negotiated with Taliban militants to win the release of 22 kidnapped South Koreans, as the latest deadline passed without word on their fate or news of progress.

A South Korean presidential envoy was due to arrive Friday for talks with Afghan President Hamid Karzai and other top officials on the crisis.

No breakthrough came in a round of telephone calls late into Thursday night that resumed Friday, officials said. Negotiators were struggling with conflicting demands made by the kidnappers, ranging from the release of Taliban prisoners to ransom money.

"We hope we will have a good result, but I don't know if they will be released today. I don't think they will be," Shirin Mangal, a spokesman for the governor of Ghazni province where the captives were taken, said Friday.

A deadline of noon Friday — the latest of several ultimatums given by the captors — came and went without fresh word of the hostages' fate. Calls to a Taliban spokesman went unanswered.

Previous deadlines have passed without incident.

In Seoul, a South Korean Foreign Ministry official, speaking on condition of anonymity because of the matter's sensitivity, said the captives were still believed to be safe and that officials were trying to get medicine and other items delivered to them.

Baek Jong-chun, a senior South Korean official, was expected to meet Karzai and other high-level officials to discuss specific measures to free the hostages, the official said.

Local tribal elders and religious clerics who have respect among the people of the Qarabagh district where the Koreans were taken have been conducting negotiations by telephone with the captors for several days.

"There are still a lot of problems among them," Qarabagh police chief Khwaja Mohammad Sidiqi said Friday.

"One says, 'Let's exchange them for my relative,' the others say, 'Let's release the women,' and yet another wants a deal for money," he said earlier.

Qari Yousef Ahmadi, who claims to speak for the hard-line Islamist Taliban, on Thursday reiterated a demand for the release of Taliban prisoners, and a threat to kill more of the hostages.

One of the group of abducted Koreans, 42-year-old pastor Bae Hyung-kyu, was found slain with multiple gunshots on Wednesday in Qarabagh.

"If Kabul administration does not solve our problem ... then we do not have any option but to kill Korean hostages," Ahmadi said by phone from an undisclosed location.

"The Taliban are not asking for money. We just want to exchange our prisoners for Korean hostages. ... When they release the Taliban, we will release the hostages," he said.

The Taliban at one point demanded that 23 jailed militants be freed in exchange for the South Koreans, though it is not clear how many militants the Taliban want freed or which ones.

Ahmadi said the hostages were being held in small groups in different locations and were being fed on bread, yogurt and rice.

The South Koreans, including 18 women, were kidnapped while on a bus trip through Ghazni on the Kabul-Kandahar highway, Afghanistan's main thoroughfare.

Their church said the abductees were not involved in any Christian missionary work in Afghanistan, and had provided only medical and other volunteer aid to distressed people in the war-ravaged country. It said it will suspend some of its volunteer work in Afghanistan.

In Washington, U.S. State Department spokesman Sean McCormack said it supports efforts to free the South Koreans.

"What should happen is that these people should be released, unconditionally, immediately and unharmed, back to South Korean authorities, so they can return back to their families," he said.