A 5-year-old Colombian girl traveling alone on a commercial flight from Bogota to New York last week was discovered carrying more than two pounds of heroin concealed in her luggage, according to U.S. Customs Service officials.

Although officials cited numerous cases of unaccompanied minors apprehended smuggling illegal drugs, they said Monday that this was believed to be by far the youngest child.

"Sending a 5-year-old girl alone on a plane to smuggle heroin represents a new low -- even for drug traffickers," said Joe Webber, the Customs special agent in charge for New York.

The name of the girl, who was turned over to a New York social services agency, was not released. Although at least one adult was at the airport to meet her, officials said the incident was still under investigation and no arrests had been made.

Officials said a relative brought the girl to the Bogota airport last Thursday and placed her aboard Colombia's Avianca Airlines Flight 020 to John F. Kennedy International Airport. They said the identity of the relative was known, but they declined to release it.

The 5-year-old was exiting the baggage area with two hard-sided suitcases when a Customs inspector stopped her for a routine check. Examining what appeared to be an unusually thick side on one of the bags, officials said, the inspector found a white, powdery substance that tested positive for heroin.

One source noted that the girl's mother had been arrested at the Miami airport in 1996 when Customs inspectors found 1 1/2 pounds of heroin packed inside the soles of her shoes. Convicted of drug smuggling, she ultimately was deported to Colombia. Neither parent's current whereabouts is known, the source said.

Drug smugglers frequently use minors as drug couriers, officials said. Two weeks ago, a 12-year-old Nigerian boy was found to have swallowed 87 condoms filled with heroin when he became sick after arriving alone on a flight from Nigeria to New York.

In December, federal authorities in Chicago indicted 35 people in connection with an alleged operation involving parents who rented their infants to smugglers who used them as a cover to carry cocaine hidden in baby formula cans from Panama, the Chicago Tribune reported.

In July 1999, an unaccompanied 9-year-old arriving in Miami on a flight from Cali, Colombia, was found with about two pounds of heroin packed in his Nintendo Gameboy and in three pairs of shoes in his luggage, a Customs official said.

"It does happen, but 5 years old shocked people," the official said. "I'm not aware of any case remotely close to this one."