United States intelligence officials warned that the terror network had showed a "persistence" in trying to master the explosive technique.
The bomb can be made by combining a number of easily obtainable chemical products. Modified buttons, zips or watches could be used as detonators. Airport security staff and airlines worldwide were warned of the new al-Qaida threat by the US Department of Homeland Security in August, the Washington Post reported.
"We judge this type of threat to be real and continuing," the department said in the warning, which was obtained by the newspaper.
The document added that there had been a "persistence (in a) line of reports from several credible, independent sources" that al-Qaida was training to build such bombs. Part of the intelligence came from confiscated al-Qaida training manuals. While small amounts of the substance called nitrocellulose would only flare up momentarily, larger amounts are explosive if tightly packed into a confined space.
Airport X-ray machines cannot detect the explosive but another type of technology, called a trace-detection machine, can.
A specially treated cotton swab is run across an item of luggage or clothing and inserted into a detector machine which gives a positive or negative result. Several thousand of the kits have been purchased by the Homeland Security Department's Transportation Security Administration in the past year.
They will be used to examine not only passengers' hand baggage, but also checked-in luggage.
Meanwhile, Osama bin Laden's son Saad is gaining increasing influence in al-Qaida, according to Western and Middle Eastern intelligence sources, raising the possibility that he is being groomed to take the reins of the terror network.
Saad bin Laden was said by intelligence officials to have been in close contact with an al-Qaida cell in the Saudi capital Riyadh in the days before the May 12 suicide bombing there, which killed 35 people.
He is also suspected of involvement in the May 16 bombings in Casablanca, Morocco, which killed 45.
It is believed that Saad is part of a small group of terror leaders managing the group from Iran, the Washington Post reported. His involvement suggests that he has won his father's trust and may one day become the new leader of the feared terror group.
The intelligence sources said Saad, who is thought to be 24, is protected by an elite Iranian security force.