The Taliban have agreed to meet Kang Sung-zu, South Korea's ambassador to Afghanistan, claiming they can no longer talk to the "insincere" Afghan negotiators.

There is time pressure on the negotiators because two of the female hostages are seriously ill and could die.

The Taliban have demanded the release of at least eight prisoners in exchange for the South Koreans.

"The South Korean government will deal with the crisis with all possibilities open, that includes the possibility of the Taliban changing its demands," Cheong Wa Dae spokesman Cheon Ho-seon said in a daily press briefing. He declined to go into more details.

The Seoul government refuses to confirm or deny reports of a direct meeting, instead reiterating it is continuing to maintain diverse "contact" with the Taliban.

It is an established policy of democratic nations that a government only negotiates with a government.