Three U.N. employees held hostage in Afghanistan were shown on Sunday in a video aired by Al Jazeera television, which said they called for the release of prisoners from Afghan jails and Guantanamo Bay in Cuba. The video showed the hostages, a man and two women, crouched on the floor with a masked militant next to them. The three appeared to be in good health. **PHOTO CAPTION*** An Afghan policeman stops a vehicle in Kabul a day after three foreign United Nations employees were kidnapped. (AFP)