An official briefed on the attack on a Detroit airliner says the U.S. has known for at least two years that the suspect in the attack could have terrorist ties.

The official tells The Associated Press that the suspect, Umar Farouk Abdul Mutallab, has been on a list that includes people with known or suspected contact or ties to a terrorist or terrorist organization.

The official spoke on condition of anonymity because the investigation is ongoing.

The list is maintained by the U.S. National Counterterrorism Center. It includes about 550,000 names.

People on the Terrorist Identities Datamart Environment list are not necessarily on the no-fly list. New York congressman Peter King says Mutallab was not on the no-fly list.