Buckingham Palace has insisted the Queen is "politically neutral" over the EU referendum, following a newspaper claim that she "backs Brexit".
The Sun quotes anonymous sources, one of whom claims to have witnessed a "bust-up" between the Queen and pro-EU former Deputy PM Nick Clegg in 2011.It says the Queen told Mr Clegg the EU was "heading in the wrong direction".
Buckingham Palace said it would not comment on "spurious" claims, and Mr Clegg called the story "nonsense".
Under the headline "Queen backs Brexit", the Sun says the Queen's exchange with Mr Clegg at a lunch in 2011 left "no room for doubt about her passionate feelings over Europe".
It says her "reprimand" of Mr Clegg "went on for some time and stunned other guests".
It claims the Queen told them: "I don't understand Europe" - words an unnamed parliamentary source says she spoke with "venom and emotion".
Analysis
A "Queen backs Brexit" headline will provoke both irritation in palace circles and a weary acceptance that it was probably inevitable that the royals would be dragged into this divisive debate.
This is an attempt to shine a light on what is rarely illuminated - the Queen's private thoughts on political matters.
Officials are keen to stress she's neither for Leave nor Remain; but on the fence, neutral and impartial - a space, they say, she's occupied for 63 years.
Their challenge is that the Queen did enter the political fray recently. It was an intervention that garnered only muted criticism. Historians may pass a different judgement.
During the 2014 Scottish referendum, the monarch was judged to have backed Scotland remaining within the UK when she told a well-wisher: "I hope people will think very carefully about the future."
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"We would never comment on spurious, anonymously sourced claims.
"The referendum will be a matter for the British people."
And Mr Clegg tweeted: "As I told the journalist this is nonsense. I've no recollection of this happening & its not the sort of thing I would forget.""
He says the Queen must remain "above the fray" of political issues, but adds: "If she has a view on Brexit, don't voters have a right to know what it is?"
Queen 'purred'
Last month a spokesman for Prince William denied the prince had been making a comment on the European debate when he described Britain as an "outward-looking nation".Newspapers including the Guardian and the Daily Mail interpreted his comments as support for Britain staying in the EU.
And in the build-up to Scotland's 2014 referendum on independence, Buckingham Palace denied suggestions that the Queen would wish to influence the result, following reports that she was concerned about the prospect of Scottish independence.
Shortly before the vote she was heard saying she hoped people would "think very carefully about the future".
After the Scottish people voted to reject independence, PM David Cameron was recorded saying the Queen "purred" on hearing the result.