U.S. doesn't believe Tehran was involved in the kidnapping of three Americans or being held in Iran.

U.S. doesn't believe Tehran was involved in the kidnapping of three Americans or being held in Iran. (DS).

Three U.S. citizens who disappeared last week in Baghdad were kidnapped and are being held by an Iranian-backed Shiite militia, two Iraqi intelligence and two U.S. government sources said Tuesday.

The U.S. sources said Washington had no reason to believe Tehran was involved in the kidnapping and does not believe the trio are being held in Iran, which borders Iraq.

"They were abducted because they are Americans, not for personal or financial reasons," one of the Iraqi intelligence sources in Baghdad said.

Unknown gunmen seized the Americans on Friday from a private residence in the capital's southeastern Dora district, according to Iraqi officials.

The State Department said on Sunday it was working with Iraqi authorities to locate Americans reported missing, without confirming they had been kidnapped.

Hostility between Tehran and Washington has eased in recent months with the lifting of crippling economic sanctions against Iran in return for compliance with a deal to curb its nuclear ambitions and a recent prisoner swap.