KABUL (Reuters) - Taliban leaders said on Sunday their fighters would kill 22 remaining South Korean hostages if the Afghan government did not release rebel prisoners by a new deadline of 0730 GMT on Monday, a spokesman said.

Taliban spokesman Qari Mohammad Yousuf said the deadline had been set by the Taliban leadership council, headed by elusive leader Mullah Mohammad Omar, giving the threat added weight.

The kidnappers killed the leader of the Korean group on Wednesday, but several further deadlines have passed without the rebels carrying out their threat to kill the remaining hostages.

“Since the talks between us, the Kabul administration and Korean government have reached deadlock and they are not honest ... hence, we will start killing the hostages if they do not start releasing our prisoners by tomorrow at 12 o’clock,” Yousuf told Reuters by telephone from an unknown location.

Sporadic talks between the Afghan government and South Korean diplomats on one side and Taliban rebels on the other have continually snagged over the rebel demand for Kabul to swap jailed insurgents for the Koreans.

Afghan President Hamid Karzai has previously ruled out any deal with the Taliban after coming under harsh criticism for freeing five rebel prisoners in exchange for the release of an Italian hostage in March.

In his first comments on the latest hostage case, Karzai condemned the kidnapping, but did not say whether any deal might be possible.

“Hostage-taking and the abuse of foreign guests, especially women, is against Islam and Afghan culture and the perpetration of this heinous act on our soil is in total contempt of our Islamic and Afghan values,” a spokesman quoted him as saying.

An Afghan minister said on Saturday force might be used if talks fail.

Pope Benedict on Sunday called the kidnapping a “grave violation of human dignity that clashes with every elementary norm of civility and rights and gravely offends divine law”.

Eighteen of the remaining hostages are women. Yousuf said some of the captives -- being held in small groups at different locations -- were sick.

Ghazni’s governor, Mirajuddin Pathan, said medicines the Korean government had wanted to send could not be delivered on Saturday because the Afghan team could not establish contact with the Taliban.

Pathan said the government did not want to use force to rescue the hostages. “We have no plan of attack. We are trying to send the delegation for more talks,” he told Reuters.

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In addition to Afghan forces, foreign troops are also stationed in Ghazni.

South Korean special envoy Baek Jong-chun met Karzai on Sunday to discuss ways to end the hostages’ ordeal.

“We are well aware of Afghan culture and the difficulties the Afghan government and people are faced with in their fight against terrorism, and will respect their decision to end the hostage crisis,” a statement by Karzai’s office quoted the Korean chief national security advisor as saying.

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The Taliban are also holding one German and four of his Afghan colleagues, abducted from a neighboring province a day before the Koreans. Another German seized alongside them was later found dead with gunshot wounds.

The abduction of the Koreans is the largest kidnapping of foreigners by the Taliban since U.S.-led and Afghan forces overthrew the movement’s radical Islamic government in 2001.

It comes amid an increase of violence in the past 18 months, the bloodiest period since Taliban’s removal.