Updated at 1:26 p.m. EST
An official briefed on the attack on a Detroit airliner said Saturday the U.S. has known for at least two years that the suspect in the attack could have terrorist ties.
The official told The Associated Press that the suspect, Umar Farouk Abdulmutallab, 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 Terrorist Identities Datamart Environment list is maintained by the U.S. National Counterterrorism Center. It includes about 550,000 names.
People on that list are not necessarily on the no-fly list. U.S. Rep. Peter King said Abdulmutallab was not on the no-fly list.
Authorities may have had further warnings of Abdulmutallab.
According to a report from the Nigerian newspaper This Day, Abdulmutallab's father took his concerns about his son's increasingly extremist religious views to the United States embassy and local authorities six months ago.
Alhaji Umaru Mutallab, a former prominent bank official in Nigeria, is about his son's alleged involvement in the bomb plot. Meanwhile, authorities in London are conducting searches throughout the city, where Abdulmutallab is reported to have attended college, according to the Daily Mail.
Mutallab said his son hadn't lived in London "for some time" but he wasn't sure exactly where he went to.
"I believe he might have been to Yemen, but we are investigating to determine that," the elder Mutallab said. He said he would provide more details later Saturday as he learned more from authorities.
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One law enforcement official said the man claimed to have been instructed by al Qaeda to detonate the plane over U.S. soil, but other law enforcement officials cautioned that such claims could not be verified immediately, and said the man may have been acting independently inspired but not specifically trained or ordered by terror groups.
All the officials spoke on condition of anonymity because the investigation was continuing.
King, the ranking Republican on the House Homeland Security Committee, said no federal air marshals were on the flights from Nigeria to Amsterdam and from Amsterdam to Detroit. Abdulmutallab did not go through full-body image screening at either airport, the congressman said.
Democratic Rep. Bennie Thompson, the chairman of the House Homeland Security Committee, said Abdulmutallab would have been re-screened at the Amsterdam airport after his flight from Nigeria. Thompson and others say the Amsterdam airport has long had a good reputation for security.
Thompson said he plans to hold a hearing in January about the incident.
"It's still safe to fly," Thompson said.
Federal officials said there would be heightened security for both domestic and international flights at airports across the country, but the intensified levels would likely be "layered," differing from location to location depending on alerts, security concerns and other factors.
Passengers can expect to see heightened screening, more bomb-sniffing dog and officer units and behavioral-detection specialists at some airports, but there will also be unspecified less visible precautions as well, officials said.
The FBI and the Homeland Security Department issued an intelligence note on Nov. 20 about the threat picture for the holiday season, which was obtained by The Associated Press. At the time, officials said they had no specific information about attack plans by al Qaeda or other terrorist groups.
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