The Taliban will continue to kidnap foreigners in Afghanistan, a purported Taliban spokesman said Monday, as Afghan doctors sent medicines for ailing South Korean hostages held by the insurgents for nearly three weeks.

An Afghan doctor who heads a private clinic said he had dropped off almost US$2,000 worth of antibiotics, vitamins and first aid kits in rural Ghazni province Sunday intended for the Koreans, two of whom are said to be extremely ill. Dr. Mohammad Hashim Wahwaj said their Taliban captors told him that they had picked up the medicines.

Qari Yousef Ahmadi, who claims to speak for the Taliban, said the lives of the 21 South Korean hostages rest in the hands of Afghan President Hamid Karzai and U.S. President George W. Bush, who are holding two days of talks at Camp David, Maryland.

"Karzai and Bush will have responsibility for whatever happens to the hostages," Ahmadi said.

A South Korean presidential spokesman, however, cautioned against expecting the summit to lead to a resolution of the hostage crisis.

"It is our government's standpoint that we should work separately from the summit to resolve the hostage issue. It is inappropriate to have any premature expectations or to overly interpret the summit," Cheon Ho-sun said in Seoul.

• More coverage of the struggle for stability is available in FOXNews.com's Afghanistan Center.

Twenty-three South Koreans from a church group were kidnapped by the Taliban on July 19 while traveling from Kabul to Kandahar to work on medical and other aid projects. Two male hostages have been executed. Among the remaining 21 hostages, 16 are women.

The Taliban have demanded that 23 militant prisoners being held by Afghanistan and at the U.S. base at Bagram be freed in return for the Koreans, but the Afghan government has all but ruled that option out.

"We will not do anything that will encourage hostage-taking, that will encourage terrorism. But we will do everything else to have them released," Karzai said in an interview broadcast on CNN Sunday.

South Korea has asked Kabul to be flexible in its policy of non-negotiation with terrorists.

Ahmadi, meanwhile, said the government's refusal to negotiate would not stop the Taliban from seizing more foreigners.

"Whether the Kabul administration will do the (prisoner) exchange or not, it will not have any effect on our side. The process of kidnapping (foreigners) will be ongoing," Ahmadi said.

Ahmadi said that the militants and South Korean officials remain in contact over the phone, but have not yet agreed on a location where they can hold negotiations over the fate of the captives.

If an agreement is not reached for in-person negotiations, then the Taliban will not be responsible for "anything bad" that happens to the hostages, Ahmadi said.

In Seoul, an official said Monday that South Korean diplomats had made contact with the captives. The official, who spoke on condition of anonymity because of the sensitivity of the issue, declined to give further details about the conversation with at least one of the captives, citing safety concerns.

About 150 demonstrators rallied at the U.S. Embassy in Seoul, praying for the hostages' release and demanding U.S. help.

In Afghanistan on Sunday, foreign and Afghan troops thwarted a Taliban ambush at a checkpoint in the south and killed 13 suspected militants. The militants were trying to attack the checkpoint on the main road linking Kabul to the southern city of Kandahar, said Ali Kheil, the spokesman for Zabul's governor.

NATO and the U.S.-led coalition did not immediately confirm the clash.

Kheil said authorities recovered 13 bodies and weapons. No Afghan or foreign troops were hurt.

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