Taliban insurgents have kidnapped 18 Koreans who were travelling on a bus in Afghanistan.

Local police chief Khowaja Mohammad Sadeeq said some other passengers on the bus were also abducted. The Taliban said they had seized 18 Koreans, 15 men and three women.

By telephone, Taliban spokesman Said Yousuf Ahmadi said: "They are safe with us, we are investigating them and our demands and reaction will be announced later."

The bus was travelling from the southern city of Kandahar to the capital Kabul when Taliban rebels stopped it in the Qarabagh district of Ghazni province, the police chief said.

In Seoul, a South Korean Foreign Ministry official said about 20 South Korean Christian volunteers were feared to have been kidnapped by Taliban insurgents.

South Korea has no combat troops in Afghanistan, only a number of engineers and doctors.

Taliban insurgents have kidnapped a number of foreign nationals as part of their campaign to overthrow the Afghan government and drive out its Western backers.

Two Germans and six Afghans were abducted southwest of Kabul on Wednesday and are still missing.

"The German citizens are safe with us. Our demand is the withdrawal of German troops from Afghanistan and also the release of our prisoners," said Taliban spokesman Yousuf Ahmadi.

Meanwhile, three British soldiers have been injured in a suicide car bomb attack in the southern Afghan province of Helmand.