Iraqi security forces sealed off part of Baghdad's southern Dora district on Monday as they searched for three US citizens reportedly abducted by gunmen.
Witnesses said the Sihha neighbourhood in Dora had been cordoned off by security forces and that helicopters were participating in the search operation. Buildings were being searched in the area, local broadcaster Alsumaria reported, quoting an unnamed security official.
Iraqi authorities set up additional temporary checkpoints and examined vehicles as the search continued for the three men, amid conflicting reports about where and when they had gone missing.
Iraqi Interior Ministry spokesman General Saad Maan said that the three had been abducted on Saturday from a "suspect apartment" - a euphemism used by the authorities for premises suspected of being used for illicit activities - in the Sihha neighbourhood.
However, a police official, who asked not to be quoted by name, earlier told dpa that the three had been kidnapped on Sunday evening by masked men in military uniform as they drove along a highway in Dora.
A senior security official, who also declined to be quoted by name, said on Sunday night that an unnamed company had reported the abduction of three US contractors on Friday.
The spokesman of the US-led coalition against Islamic State, Colonel Steve Warren, said that the three were civilian contractors working with the US army.
Kidnappings are common in Iraq. Powerful Shiite Islamist militias, which give government forces key backing against the Sunni extremist Islamic State organization, have frequently been accused of responsibility for many of the incidents.
Gunmen abducted a number of Qatari nationals who were on a hunting trip in mid-December in the southern desert near the Saudi border. They remain missing.