The Taliban said it would not back down from its leader's 8:30 am British time final deadline on Monday and would kill the 22 South Korean hostages unless the Afghan government freed jailed rebels by then.

Monday's deadline was issued by the Taliban leadership council, led by elusive Taliban leader Mullah Mohammad Omar, giving the threat to kill the hostages more weight than several other deadlines that have passed without incident.

Taliban sources said the government had made no contact since the final deadline was issued by the movement's leadership council on Sunday and reiterated there would no backing-down.

"We will not back down from the deadline and the government has not established contact with us," Taliban spokesman Qari Mohammad Yousuf said by telephone from an unknown location.

The Taliban seized the Korean Christians more than 10 days ago from a bus in Ghazni province to the southwest of Kabul and killed the leader of the group on Wednesday after a deadline.

That prompted the Afghan government to seek more talks with the Taliban who said the release of a group of militants held by Kabul was the only way out of the crisis.

On Sunday, the Taliban ruled out holding further talks after they said government negotiators demanded the unconditional release of the hostages and a senior official hinted that force will be used to rescue them.

The Afghan government had wanted the Taliban to first release the 18 women hostages, but the insurgents demanded the government release its prisoners first, leading to deadlock, a Kabul-based Western security analyst said on condition of anonymity.

President Hamid Karzai has remained silent throughout the hostage ordeal, except for condemning the abduction, the largest by the Taliban since U.S.-led forces overthrew the movement's radical Islamic government in 2001.

He came under harsh criticism for freeing a group of Taliban in March in exchange for the release of an Italian journalist.

The abduction of the Koreans came a day after two German aid workers and their five Afghan colleagues were seized by Taliban in neighbouring Wardak province.

The body of one of the Germans has been found with gun shots and the Taliban still hold the other along with four Afghans.