A United Airlines flight had an unexpected landing at Beijing International Airport on Saturday after a pregnant woman had a miscarriage on board.

The American woman, named Sally, was taken to hospital in an ambulance. After two hours of emergency treatment she was said to be out of danger. She stayed at the hospital for one night and left yesterday morning, said a nurse at the Sino-Japanese Friendship Hospital, who preferred not to be named.

"The woman had carried the baby for quite a few months before the emergency," the nurse added.

Sally and her husband Peter, who declined to reveal their surname, had travelled around China for two weeks before boarding a flight in Hong Kong bound for Chicago at around 1 pm on Saturday.

They had flown for about two hours when Sally began to haemorrhage, according to the Chinese-language Beijing Morning Post.

At around 4 pm Beijing International Airport received a request from the captain of the flight for a forced landing, said the newspaper report.

The request was approved and the plane landed safely at 4:45 pm.An ambulance was waiting and took the American couple to the Sino-Japanese Friendship Hospital, one of the best hospitals in Beijing.

The plane departed half an hour after the couple were taken off.