Some reports put Sajida Khairallah Telfah in Syria, said defense and other U.S. officials, speaking on condition of anonymity. One official said other reports put her in other countries, which the official would not specify.
It is unclear when she left Iraq.
As early as April 2, Defense Secretary Donald H. Rumsfeld spoke of unconfirmed reports that members of the Iraqi president's family had fled, including his first wife. The officials said Monday that information has become significantly more solid since then.
The whereabouts and status of other members of Saddam's immediate family likewise are not known. Nor do officials have definitive word on Saddam or his elder sons, Odai and Qusai, both senior leaders in Saddam's administration.
Other members of Saddam's family may have information on their whereabouts, including Saddam's second wife, three daughters and another son, officials said. All kept low profiles during Saddam's rule, and none held senior positions.
Saddam's first wife was mother to Odai, Qusai and three daughters: Raghad, Saddam's favorite; Rana; and Hala. Some of the children have children of their own. Saddam remains married to both wives. In Islam, a man may have as many as four wives.
In 1995, Raghad's and Rana's husbands defected from Iraq to Jordan. The brothers were debriefed by Western intelligence officials and reportedly disclosed secrets of Iraq's military and weapons programs.
They failed to gain the trust of Iraqi exiles, however, and returned to Baghdad with their families six months later on Saddam's promise neither they nor their families would be harmed. They were shot down shortly after they arrived, and Saddam placed Sajida under house arrest because she demanded that he punish the killers. Opponents said they were instigated by Odai.
Saddam's second wife, Samira Shahbandar, was mother to Saddam's other son, Ali Saddam Hussein. Saddam married Shahbandar, a daughter of a prominent Iraqi family, in the late 1980s, and their son is not believed to be old enough to have any responsibilities.
Saddam's half brother, Watban Ibrahim Hasan, an adviser to the Iraqi president, was captured near Mosul in recent days, apparently preparing to flee to Syria, U.S. officials said.
Bush administration officials have alleged that Syria is taking in members of Saddam's regime. They have provided no examples other than to raise the possibility that Saddam's wife went there.