Families are reportedly offered money for their children |
Some 50 children from the northern province of Badakhshan were intercepted by police as they travelled by road through neighbouring Takhar.
The authorities suspect the boys were destined for religious schools in Pakistan and Iran, although there are concerns they might have been taken for sale as sex slaves.
Afghan officials said eight people had been arrested on suspicion of smuggling boys.
The United Nations child agency Unicef has warned of a serious problem of child abduction in Afghanistan, which has limited resources to deal with the problem.
'Brainwashing'
Unicef has urged the Afghan Interior Minister, Ali Ahmad Jalali, to intervene.
Since the fall of the Taleban, Afghanistan's transitional government has been attempting to rebuild the police force and national army, which disintegrated during two decades of civil war.
"We suspect there may be other children who have been abducted," Unicef spokesman Edward Carwardine said.
"We also have unconfirmed reports from the south that children have been going missing there."
According to the agency, many children abducted in the region are sold as sex slaves or child labourers.
A senior Afghan intelligence chief, Amrullah Saleh, told the Associated Press that people from Pakistan "with pockets full of cash" often travelled to remote areas of Afghanistan. They promised poor people "good religious education and divine enlightenment for their children," he said.
Boys were then smuggled across the border to religious schools in tribal regions of Pakistan, where they were "brainwashed, mentally, physically and sexually abused... thus becoming a weapon of Pakistan's intelligence and religious parties," he said.
The power of Afghan President Hamid Karzai does not extend much beyond Kabul and provinces are ruled by warlords who maintain small private armies.
