GHAZNI, Aug 5: Taliban militants again threatened on Sunday to kill more of their 21 South Korean hostages, as Seoul said it hoped the Afghan and US presidents could help secure their release.

The fresh threat from the hardline Islamists — the first since Wednesday, when their last deadline expired — came as Afghan President Hamid Karzai prepared to meet his US counterpart George W. Bush at Camp David.

Earlier, a South Korean official said he hoped the two leaders could break the apparent deadlock in negotiations for the release of the 21 aid workers, who were abducted in volatile southern Ghazni province on July 19.

Taliban spokesman Yousuf Ahmadi, apparently frustrated with the lack of progress in the hostage talks, said more of the captives could be murdered at “any time.” “In the past two days there has not been any contact between us and the Koreans or the Kabul administration,” he told by telephone.

“So the killing of the hostages is inevitable and since we've not set a deadline for them they could be killed at any moment, any time,” he said.

The militants have already killed two men belonging to the team of Korean aid workers, who were nabbed on the Kabul-Kandahar highway, considered a no-go area by many foreigners amid deteriorating security across the country.

“If they want the hostages to stay safe, they have to really hurry otherwise they could be killed at any second,” Ahmadi warned.

But he also said the Taliban were ready to meet with South Korean negotiators in “areas under control of the Taliban” or in another country, so long as the Taliban representatives received a UN guarantee of safe return.

The Karzai-Bush talks have been seen as crucial to the ongoing hostage negotiations. Kabul, apparently backed by Washington, is refusing the Taliban's demand for the release of jailed militants in exchange for the hostages.

“We are hopeful of any positive outcome from the meeting,” an official at the South Korean embassy in Kabul said of the meeting between the two leaders at Bush's presidential retreat.

“It is the decision of the Afghan government. We want to solve this in a peaceful and constructive way,” the official said, requesting anonymity.

Afghan negotiators again Saturday ruled out a prisoner exchange and said any deal to free the group would have to involve a ransom payout.

The South Korean embassy official said: “We have contact but we cannot confirm the channel. We are using all possible means to mobilise help or support from all over the world.” The Afghan interior ministry said meanwhile officials were doing what they could.

“We will not spare any efforts for their safe release,” ministry spokesman Zemarai Bashary said, while refusing to be drawn on whether the use of force was a possibility.

“We will try to solve this through talking. We cannot clearly say what we would do if the negotiations fail,” he said.

The South Korean official and families of the captives in Seoul refused to comment on an emotional plea for help on Saturday from a purported hostage whom a Taliban spokesman put into contact with AFP.

“I don't want to die. We want to go home,” the woman said by telephone from an undisclosed location. “I don't know how long we can survive.” There was no way to verify whether the woman was in fact one of the aid workers.

The call appears to have been aimed at intensifying pressure on the Afghan government as talks on the fate of the hostages seem to be stalled.

Washington, the main supplier of international troops now helping Kabul to fight back the rebels, was a leading critic of a prisoner exchange in March that freed an Italian hostage but put top Taliban back in the fray.

Karzai vowed then that such a deal would not be repeated and critics said it would likely increase kidnappings by militants and criminals alike.

Militants said to be allied to the Taliban are still holding a 62-year-old German engineer and four Afghans who were captured a day before the South Koreans. They have publicly demanded a prisoner swap for his freedom.

—AFP