BAGHDAD — After being held captive for a month, three Americans who were kidnapped in the Iraqi capital have been freed.

Saad al-Hadithi, a spokesman for the prime minister’s office, confirmed that the three had been released but said he had no further details. The State Department said it welcomed the release and thanked Iraqi authorities for their assistance.

The Americans, two men and a woman, were working as contractors training Iraqi security forces, according to an Iraqi security official. Apparently, on an unauthorized trip off base, they were seized in the Dora neighborhood in southern Baghdad in an apartment the Iraqi police described as ‘‘suspicious.’’ Some residents described it as a brothel, but details of the kidnapping have remained murky. Other reports have said the group was visiting the home of their Iraqi interpreter.

Shi’ite militias have a strong presence in the area, a sprawling mixed neighborhood that suffered some of Iraq’s worst violence during the sectarian bloodletting that followed the 2003 US invasion. Armed gunmen regularly carry out raids and take it upon themselves to enforce moral codes, leading to suspicions that such a group was behind the abduction.

Since a call to arms to defend the country from the advance of Islamic State militants in 2014, Shi’ite militias have operated with increasing impunity. Iraqi officials have expressed concerns about how they will be brought back under state control.

Washington Post