Detectives are investigating after a woman allegedly sexually assaulted two female British airline cabin crew at a party.
The women told a friend that they had consumed drugs before the raid on a Los Angeles mansion.
The pair – who were in the city as part of their job – said they had gone there after visiting a nightclub.
It is said that at least one woman shed tears during the flight back to London and told colleagues about the incident.
A “third person” notified authorities at Heathrow when a Metropolitan Police plane landed, saying an investigation was underway.
A source said of the alleged incident: “Women were working abroad and let their hair down one evening. He went to a luxury club in Los Angeles and from there he went back to the mansion.
“He says he was drugged and sexually assaulted while in the mansion. It was very serious.”
Women have worked for their airline for many years, providing them with expert help and support.
An unidentified company spokesman said: “We are aware of reports that staff members may have been involved in the incident while abroad.
“We take such matters very seriously and are fully supportive of them.”
The Met said: “Heathrow police were told by a third person that two members of an incoming airline cabin crew had been sexually assaulted in the US.
“Our inquiries are ongoing.”