Baghdad (CNN) -- An American said to have been held captive for months was turned over Saturday to the U.S. Embassy, a United Nations spokeswoman said.
The man had been earlier handed over to the U.N. office in Baghdad by a movement led by radical Shiite cleric Muqtada al-Sadr, the U.N. mission in Iraq said.
Two political leaders of the al-Sadr movement identified the American as Randy Michael.
The man, wearing a military uniform, spoke to reporters in Baghdad on Saturday, but did not provide his name. He said he deployed to Iraq in 2003 and spent 15 months in a military capacity.
"At which time, I moved to a civilian capacity from then until June 18, 2011, when I was taken hostage by elements of Yom al-Maoud under the direction of Sayyed Muqtada al-Sadr," he said, adding that he was taken inside the capital and kept at various locations within the city. Yom al-Maoud is also known as the Promised Day Brigade.
"It was explained to me that my release has been for more of humanitarian reasons and that there was no exchange involved," the man said.
A U.S. State Department official confirmed that the United Nations transferred a citizen to the U.S. Embassy in Baghdad. That person is being provided with consular services, the official said, declining to offer details, including the citizen's name.
Maha al-Douri, a lawmaker and a member of the al-Sadr movement, said Michael had been in captivity for nine months. A spokesman for the U.S. Embassy in Baghdad said officials were working "to verify the information regarding the alleged U.S. captive."
A Pentagon official said the Defense Department is also looking into the reports, but added that to the best of defense officials' knowledge, no active duty military person has been missing in Iraq.
The website of the Defense Prisoner Of War/ Missing Personnel Office on Saturday showed three Defense Department contractors as still missing from Operation Iraqi Freedom. Michael was not among them.
The al-Sadr movement was a middleman between an armed group and the United Nations to facilitate the release of Michael, al-Douri said.
The handover was "meant to show the goodwill of Iraq to the American people" following the withdrawal of U.S. troops from the country, said Bahaa al-Aaraji, head of the movement's Ahrar bloc.
Al-Aaraji said the man was "captured in battles," but had no further information.
Journalist Mohammed Lazem and CNN's Gregory Clary, Michael Martinez and Barbara Starr contributed to this report.