Said Yousuf Ahmadi, speaking by phone, said: "They are safe with us, we are investigating them and our demands and reaction will be announced later."
The bus was stopped on Thursday in the Qarabagh district of Ghazni province, Khowaja Mohammad Sadeeq, the local police chief, said.
Confirmation came after the South Korean foreign ministry in Seoul said that it was "highly likely" that South Koreans Christian volunteers had been snatched.
Troops
South Korea has no combat troops in Afghanistan, only a contingent of engineers and doctors.
"They did not contact us, police or the security forces for protection while travelling in this region"
Mirajuddin Pattan, governor of Ghazni province |
Mirajuddin Pattan, Ghazni governor, expressed anger at the presence in his part of the country of such a large number of foreign nationals.
Speaking to AFP news agency, Pattan said: "They must have thought they are in Korea, not in war-torn Afghanistan.
"They did not contact us, police or the security forces for protection while travelling in this region."
The Taliban has seized a number of foreign nationals as part of its campaign to overthrow the Afghan government and drive out its Western backers.
Demands
Two Germans and six Afghans were seized southwest of Kabul on Wednesday and are still missing.
Ahmadi said: "The German citizens are safe with us [the Taliban]. Our demand is the withdrawal of German troops from Afghanistan and also the release of our prisoners."
One German national was kidnapped in western Afghanistan this month, but was released unharmed after few days.
Taliban fighters seized two French aid workers and three of their Afghan colleagues in southwestern Afghanistan in April but later released them unharmed.