A sick passenger aboard a flight from Los Angeles to Japan prompted authorities to quarantine at least 35 passengers and two flight attendants shortly after the plane landed at Tokyo's Narita airport, a pilots union spokesman said on Monday.

Sam Mayer, spokesman for the Allied Pilots Association, told NBC that the passengers and flight attendants from American Airlines flight 169 from Los Angeles International Airport (LAX) were taken to a quarantine facility near Narita Airport near Tokyo.

Airline officials could not be reached for immediate comment, but the NBC station quoted an anonymous airline source as saying that a sick passenger aboard the flight raised the concern of Japanese health officials.

Passengers who were sitting near the sick person and flight attendants working the same section of the aircraft were detained when the flight landed, the source said.

The sick passenger was identified as a Japanese woman who was returning from a vacation in Las Vegas.

The flight left LAX on Sunday afternoon and arrived at Tokyo's Narita airport earlier on Monday.

Three cases of A/H1N1 virus, previously known as swine flu, have been confirmed in the Los Angeles area.