Afghanistan's Taliban began the first round of face-to-face talks with a South Korean team on Friday over the 21 hostages the group is holding, an Afghan official said.

The talks were held in an area under the control of the Afghan government in Ghazni province, a provincial official said.

Earlier, a Taliban spokesman Qari Mohammad Yousuf said the meeting was expected in Ghazni and Kabul has guaranteed the safety of the Taliban negotiators.

"The meeting will start after a short while. The team (Taliban) has gone to Ghazni on the basis of a written guarantee of the Kabul administration," Yousuf told Reuters by phone from an unknown location.

"As long as the talks continue, there will be no problem for the hostages."

The South Korean team was not available for comment.

The Taliban kidnapped 23 Korean Christian volunteers, 18 of them women, more than three weeks ago from a bus in Ghazni which lies some 140 kms (87 miles) to the southwest of Kabul.

The group killed two male captives after deadlines passed without their demands being met, which prompted South Korea to seek face-to-face talks with the Taliban. Its main demand is the release of Taliban prisoners held by Kabul.

Seoul says it has no power to free jailed Taliban and President Hamid Karzai's government has ruled out any swap of prisoners after it came under harsh criticism for freeing a group of Taliban in return for an Italian journalist in March.

Afghan government officials have said that force might be used to rescue the hostages if the talks fail, and have sent troops to Ghazni.

The Taliban have divided the hostages into several groups and have said any use of force to free them would put their lives at risk.