Bomber became suspect in the air

Administration officials said they had flagged Umar Farouk

Abdulmutallab as someone who should go through additional security screening upon landing.

The bomber's potential ties to extremists came up in a routine check of passengers en route to the US from overseas – and not because of any suddenly gathered intelligence that emerged during the flight.

The news came as President Barack Obama prepared to outline government mistakes in the near-catastrophe and order solutions.

The White House is to make public a declassified account of how Abdulmutallab slipped through post-September 11 security to board the plane with an explosive.

Mr Obama's national security adviser said that people who read the report will feel a "certain shock" about all the missed warning signs.

Mr Obama will publicly address the US about the findings. A government official said the president will order US agencies to move faster and more accurately in adding suspects to a watch list designed to stop terrorists before they strike.

That would mean that people with potential ties to terrorist organisations or violent extremists, would be included in the watch list more rapidly.

The government's much smaller "no-fly" list is drawn from the most troubling names on the watch list. It was expected that building up the lists would require additional resources.

Mr Obama's move follows a promise earlier in the week to reveal new steps to thwart future terror plots.

No firings over the December security debacle are expected – for now, at least.

In an interview in the USA Today newspaper, national security adviser General James Jones said people who read the report will "be surprised that these correlations weren't made" between clues pointing toward a threat from Abdulmutallab.

Even though the 23-year-old Nigerian man was in a database of possible terrorists, he managed to fly from Nigeria through Amsterdam to Detroit with an explosive concealed on his body.

Customs and Border Protection officials screen passengers against terrorist watch lists before international flights leave for the US, then check names against a different database while the flight is in the air.

It was during this second check that officials caught information Abdulmutallab's father had provided to the US embassy in Nigeria a month earlier, warning the US that his son had drifted into extremism in the al-Qaida hotbed of Yemen.

Even if customs had given Abdulmutallab extra scrutiny when he landed in Detroit, there was no guarantee that the information provided by his father would have been enough for an officer to decide he should not be allowed in the country.

Abdulmutallab's name was one in about 550,000 of an intelligence

database of people with suspected terrorist ties.

There was not enough information about Abdulmutallab's switch to terrorism to get him onto a subset of the list where he would have been flagged in initial screening.

An even stricter "no-fly" list contains about 3,400 names.