An American suspected of flying from Buenos Aires with dynamite in his luggage was detained by FBI officials in Houston after bomb-sniffing dogs picked up a scent in his luggage.
The FBI said he was a college student who carried what appeared to be a small stick of dynamite. The man was detained for questioning in the customs area of the Houston airport.
"Sometimes there is a good explanation for why something is brought in, but he may still be charged for bringing explosives onto an aircraft, which is against the law," said FBI Special Agent Shauna Dunlap.
The flight was Continental Airlines flight 52, which was searched in Houston and again as a precaution on arrival in Newark, New Jersey.
It was the latest in a series of scares - at least three of them yesterday - since police in Britain uncovered a suspected plot to blow up US-bound airliners this month.
Since then security has been tightened at airports and passengers have been jittery.
In Buenos Aires, Marcelo Sain, head of Argentina's Airport Security Police, told local TV that authorities found "a Coca Cola bottle with mud, and inside it was a tube with ammonium nitrate, a little bit of dynamite and a detonator."
Mark Mancuso, deputy director for public safety at Houston airports, said the man told authorities the items were souvenirs purchased at a mine in Bolivia.