The Taliban are willing to swap two of its female South Korean hostages for two jailed women who are supporters of the insurgents, according to a purported spokesman for the group.

In an interview from an unknown location, Qari Yousef Ahmadi repeated that two of the female hostages are gravely ill.

But he said the insurgents will trade them for two imprisoned Afghan women who he says are in jail for providing food and shelter to Taliban fighters.

The militants, who seized 23 South Korean aid workers nearly three weeks ago, have already killed two male hostages to back their demands to exchange the hostages for jailed insurgents.

South Korea's foreign minister said on Tuesday he doesn't believe the two female hostages are as seriously ill as the Taliban claims.

"The health problems of two female hostages, said to be in critical condition in domestic and foreign media reports, are not serious," Song Min-soon told reporters.

"The hostages can't be perfectly healthy after nearly 20 days in captivity. In that sense, they are not healthy on the whole. There has been no symptom of any of the hostages being critically ill."

Min-soon's comments come as diplomats from South Korea confirmed they had direct contact with at least one and as many as three hostages over the weekend.

Officials offered few details on the contact, citing potential risk to the hostages.

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.

They say the Koreans have assured them South Korean President Roh Moo-hyun is pressuring the U.S. to help free jailed insurgents in exchange for the hostages. 

But Afghanistan and the U.S have steadfastly refused to make concessions to the insurgents, saying that there should be no quid pro quo for the release of hostages.