The three were kidnapped from an area called al-Haritha, north of Basra, Mohammed al-Mussawi, the local police chief said. They were travelling in a black Opel car when three other vehicles full of gunmen ambushed them and kidnapped them, police said.
The American brought to six the number of private security contractors now held hostage in Iraq, after four Americans and an Austrian were kidnapped on November 16 from Safwan, near Basra.
The latter group was escorting a convoy on behalf of Kuwaiti-based Crescent Security when they were seized by men wearing police uniforms.
Their captors released a video earlier this week in which they appeared healthy but showed the hostages asking for the release of all detainees in American- and British-run prisons in Iraq.
Several groups are fighting against US-led forces in Iraq, along with illegal militias, corrupt security force units and criminal gangs who seize hostages for ransom.