The British Film Institute is investigating whether footage of the Queen performing a Nazi salute was leaked from its headquarters.
The 17-second video of the Queen as a child performing the gesture was released by The Sun.
The BFI - who has been working to digitise some of the Royal Family's home videos - are working, along with Buckingham Palace and the Royal Collection Trust, to establish how the footage came into the hands of the newspaper.
A BFI spokeswoman said the organisation was continuing to "investigate".
The footage showing the Queen performing a Nazi salute as a child could have been accidentally leaked by Buckingham Palace.
The edited clip from 1933 showing Princess Elizabeth and her sister Margaret was allegedly used in an exhibition at the Palace last year and may have been inadvertently released to a documentary maker after a flurry of requests for the unseen royal home movies, according to the Daily Telegraph.
Buckingham Palace, which has launched an inquiry into how the film reached The Sun, is considering taking legal action over the footage.
A spokesman for Buckingham Palace said: "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."
John Whittingdale, the culture secretary, has said The Sun's decision to publish images of the Queen as a child performing a Nazi salute was an "editorial judgement" the paper was entitled to make, but that he understands why the Palace is upset.
Asked on BBC1's Andrew Marr Show if The Sun had been right to publish the story, Whittingdale responded:
"That is a matter for The Sun. It is an editorial judgement. It is up to the press to decide what is and what is not appropriate to print.
"They decided clearly there was a public interest and the British public will judge whether or not they were right ... But I can understand, in this particular instance, why the Palace were upset by it."
Buckingham Palace is considering taking legal action over leaked footage that shows the Queen as a child performing a Nazi salute with her family.
The Palace has launched an inquiry into how the 17-second black and white film came into the hands of The Sun newspaper.
It shows the Queen, aged six or seven, join the Queen Mother and her uncle Prince Edward in raising an arm in salute as she played alongside her younger sister, Princess Margaret.
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The Queen has spoken of the "horrific" scenes British forces faced when they liberated the Bergen-Belsen concentration camp as she visited the notorious site.
At the camp in northern Germany where 70,000 people died from disease, starvation or brutal mistreatment, the Queen and Duke of Edinburgh paid their respects by laying a wreath.
With quiet dignity and the minimum of protocol, the royal couple toured the site which was razed to the ground and is now a museum and memorial to those who died during the Second World War.
ITV News Royal Editor Tim Ewart reports:
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