Footage showing Queen Elizabeth giving a Nazi salute as a child could have been accidentally leaked by Buckingham Palace.
The clip showing Princess Elizabeth and her sister Margaret seconds after the incident was reportedly used in an exhibition at the palace last year.
It may have been released to a documentary-maker after a flurry of requests for the unseen royal home movies, according to reports.
Buckingham Palace is considering taking legal action over the footage, and has launched an inquiry into how the 17- second black and white film came into the hands of the media.
"There is an inquiry going on to find the source of the footage and until that inquiry is completed we would not give out any further information," said a palace spokesman.
The grainy footage from 1933 shows the Queen, aged six or seven, playing with a dog on the lawn in the gardens of Balmoral, the Sun claims, before she raises an arm to wave to the camera with Margaret.
The Queen Mother then makes a Nazi salute and, after glancing towards her mother, the Queen mimics the gesture.
Her mother repeats the salute, joined by her uncle Prince Edward, the future King Edward VIII, and Margaret raises her left hand before the two children continue dancing and playing on the grass.
Some have criticised the decision to publish the footage, but a Palace source has said the pictures should be seen "in their proper context and time".