South Korean officials have talked with at least one of 21 surviving aid workers held hostage in Afghanistan, as negotiations to free the captives remain deadlocked Monday.

Diplomats from South Korea confirmed they had direct contact with at least one and as many as three hostages over the weekend.

South Korean students struggle with riot police officers during a rally in Seoul on Monday demanding the United States engage in negotiations for the safe return of South Korean hostages in Afghanistan.
(Lee Jin-man/Associated Press)

Officials offered few details on the contact, citing potential risk to the hostages. It's the first direct contact South Korean officials have had with the captured aid workers.

The aid workers were seized from their bus on July 20. Since then, the Taliban have killed two male hostages while demanding the release of jailed Taliban militants.

Four days of negotiations on potential talks between South Korean officials and Taliban representatives were stalled Monday over where the meeting would take place.

The insurgents are demanding the meeting be held in territory under their control or in a safe place guaranteed by the United Nations.

"We are trying to find a solution," said a local lawmaker brokering the talks. He said the Taliban and the Korean ambassador are in contact over the phone.

No reward: White House

Taliban officials have also reportedly demanded U.S. President George W. Bush and Afghan President Hamid Karzai, who held talks at Camp David Monday, agree to free the Taliban prisoners.

However, a White House representative who spoke after Bush and Karzai met said the two men agreed the Taliban should not get concessions in exchange for the hostages.

"Both leaders agreed that in negotiations for the release, there should be no quid pro quo for the hostages. The Taliban are brutal and should not be emboldened by this," said Gordon Johndroe.

Anti-American activists have blamed the kidnappings on South Korea's military alliance with the United States. Students battled police in front of an American military base in South Korea on Monday, while about 100 protesters held peaceful demonstrations outside U.S. and Afghan embassies in Seoul.

Afghan doctors treat hostages

Meanwhile, Afghan doctors on Monday delivered medicine to the 18 women and three men being held.

One of the female hostages, a 32-year-old nurse, said the captives were ill and asked UN Secretary General Ban Ki-moon for help Saturday on Voice of America radio. 

"We are innocent people," she said. "We came here to help the people, but now we are all sick…. Dear Mr. General Secretary Ban Ki-moon please save us…. We don't want to die."

The Taliban say more hostages will die unless their demands are met. 

Afghan officials, though, continue to refuse to release jailed insurgents, saying it would encourage what they call a kidnapping "industry."

With files from the Associated Press