The crew member was reportedly arrested and is believed to still be in police custody, reports Mail Online.
A BA insider told the newspaper: “There was an incident involving a female and male crew member.
BA sources said the incident took place earlier this week following a 12-hour flight from London‘s Heathrow Airport to Singapore.
After making the rape allegation, the stewardess, said to be a senior female flight attendant, was moved from the usual crew hotel The Jen Tanglin in the city and given a room at a separate hotel.
A British Airways crew member has been arrested on suspicion of raping an air stewardess after an off duty drinks party while on a stopover in Singapore- Mailonline
“BA had to send out a manager and replacement crew so the flight to Sydney could continue and manage the crisis.”
A British Airways spokeswoman said: “We are co-operating with the police investigation and are offering our full support to our cabin crew.
“As it is a live investigation we won’t be commenting further.”
They are usually on lower wages than more senior crew.
Last year BA bosses warned mixed crew fleets that drunken antics were getting so bad that they were affecting the airline’s reputation and ability to deliver a first class service to passengers.