(CNN) — WASHINGTON (CNN) -- The Federal Aviation Administration said Friday that it is looking into allegations that passengers onboard singer Justin Bieber's charter flight last week interfered with the flight crew.
Under FAA regulations, "No person may assault, threaten, intimidate, or interfere with a crew member in the performance of the crew member's duties aboard an aircraft."
According to a law enforcement sources, Bieber and his father were "extremely abusive verbally" to a flight attendant during a flight on the chartered Gulfstream IV aircraft from Ontario, Canada, to Teterboro Airport in New Jersey last Friday in advance of the Super Bowl.
Justin Bieber and his father refused a pilot's repeated warnings to stop smoking pot on the flight, according to a report by U.S. Customs and Border Protection, which was read to CNN,
The pilots asked the flight attendant to remain in the cockpit to protect her from the alleged abusive behavior, the report says.
Law enforcement sources told CNN that the pilots donned oxygen masks to keep them from inhaling the pot smoke. The pilots were concerned the smoke would result in them failing drug tests, law enforcement sources told CNN.
After the jet landed at Teterboro, federal agents from CBP, the Drug Enforcement Administration and Immigration and Customs Enforcement said they detected the odor of marijuana, which prompted a search by drug-sniffing dogs, the source said. No drugs were found, a law enforcement source told CNN.
Bieber, 19, a citizen of Canada living in the United States on a work visa, was detained by border agents for several hours of questioning to determine if he was admissible to the United States. Bieber and his entourage of 10 were granted re-entry.
Authorities said both civil and criminal statues prohibit passengers from interfering with the a flight crew in the performance of their duties. Under a civil statute, violators face penalties of $11,000 to $27,500, the FAA said. Under a criminal statute, violators face a maximum of 20 years in prison and fines up to $250,000.
It is not clear how the case came to the FAA's attention. The agency declined to say whether they were alerted by complaints from the pilots, by media reports, or by the investigating CBP officers or others.
In a statement to CNN on Friday, the FAA said it is "looking into allegations" that passengers on the plane interfered with the flight crew, but it did not identify specific passengers.
A representative for the pop star had no comment Friday night.
Bieber has had several encounters with law enforcement authorities in recent months. He was recently arrested in Toronto, accused of assaulting his limousine driver in December.
He also faces charges of drunken driving, resisting arrest and driving on an expired license after being stopped by police in Miami Beach, Florida, last month.
The Los Angeles County district attorney is considering whether to charge Bieber with felony vandalism in the egging of his neighbor's house on January 9, 2014.