Buckingham Palace has laid an official complaint with Britain's press watchdog over a newspaper report that Queen Elizabeth backs a British exit from the European Union.
Under the front-page headline "Queen backs Brexit", The Sun newspaper on Wednesday quoted unidentified sources as saying the Queen had made her opposition to British membership of the EU clear on at least two occasions over the past decade.
"The Queen remains politically neutral, as she has for 63 years," the palace said in a statement.
"We will not comment on spurious, anonymously sourced claims.
"The referendum is a matter for the British people to decide."
It said aides had written to the chairman of the Independent Press Standards Organisation to complain, citing a clause of the editors' code of conduct relating to accuracy.
Opinion polls show voters are divided over membership ahead of a June 23 referendum so even the perception that the Queen, who must remain above politics under Britain's unwritten constitution, may favour an exit from the 28-member bloc could be damaging for the campaign to keep Britain in.
The Sun, owned by Rupert Murdoch's News Corp, reported the Queen had told then Deputy Prime Minister Nick Clegg at a Windsor Castle lunch in 2011 that the EU was heading in the wrong direction.
Mr Clegg denied the report via Twitter, saying: "I've no recollection of this happening & its not the sort of thing I would forget."
Britain's best-selling daily has repeatedly criticised the country's EU membership.
The report also said the monarch told lawmakers at a separate meeting that she did not understand Europe.
"The Sun stands by its story, provided by a very credible source," a spokesman said.
The Queen is not the first royal to have been pulled into the EU debate. Prince William was criticised by some papers, including The Sun, over a speech he gave to British diplomats last month about the importance of Britain working with other nations.