The US embassy in Baghdad has confirmed that "several" Americans were kidnapped there.
"We are working with the full co-operation of the Iraqi authorities to locate and recover the individuals," BBC quoted a state department official as saying on Monday.
Unconfirmed reports from Iraqi security circles said three Americans and an Iraqi translator were abducted from the southern side of Baghdad.
But the US officials did not say how many were held or where they were seized.
"A company filed a report on Sunday about three of its staff going missing two days ago. They are American contractors. We are looking into this report," the senior security official said.
"The safety and security of American citizens overseas is our highest priority," said US state department official John Kirby.