LONDON • Buckingham Palace has filed a complaint with a British press standards group over a front-page story in Mr Rupert Murdoch's The Sun tabloid, which reported that Queen Elizabeth II voiced doubts about Britain remaining in the European Union.

The Sun, citing anonymous sources, reported on Tuesday that the Queen had made her scepticism of the EU known during a lunch at Windsor Castle with Mr Nick Clegg, who was the deputy prime minister under the previous government, and at a reception at Buckingham Palace with members of Parliament. The newspaper did not provide dates or any other details of the two occasions.

A spokesman for the royal family denied the report. "The Queen remains politically neutral, as she has for 63 years," the spokesman said on Tuesday evening, speaking on the condition of anonymity under palace rules. "We will not comment on spurious, anonymously sourced claims. The referendum is a matter for the British people to decide."

The complaint with the Independent Press Standards Organisation cited an accuracy clause in the group's Editors' Code of Practice, according to a statement from the palace.

Mr Clegg on Wednesday also rebutted The Sun's report. "As I told the journalist, this is nonsense," he posted on Twitter. "I've no recollection of this happening and it's not the sort of thing I would forget," the pro-EU lawmaker wrote.

The story touched nerves because British voters are about to decide whether to remain in the EU.

The Sun said it will not retract the report. "The Sun stands by its story, which was based on two impeccable sources and presented in a robust, accessible fashion," the newspaper said in a statement. "The Sun will defend this complaint vigorously."

Polls indicate the result of the June 23 referendum could be close.

Prime Minister David Cameron is leading the campaign to stay in the political union, while fellow Conservative Party member and London Mayor Boris Johnson supports a so-called Brexit.

The pound saw its biggest drop against the euro in almost two weeks on Tuesday, as the Bank of England Governor Mark Carney said Britain's potential exit from the European Union would hurt the City of London and heighten risks to financial stability.

The Queen, who acceded to the throne in 1952 and in September became the longest-reigning monarch in British history, is expected to stay out of politics under Britain's unwritten Constitution.

BLOOMBERG, NEW YORK TIMES