The Sun has said it stands by its story about the Queen voicing strong Eurosceptic views after Buckingham Palace said it has written to the press watchdog to register a complaint over the claims.
The newspaper said the Queen vented her anger with Brussels at the pro-EU former deputy prime minister Nick Clegg during a lunch at Windsor Castle in 2011.
In a statement, the Sun said: "The Sun stands by its story, which was based upon two impeccable sources and presented in a robust, accessible fashion. The Sun will defend this complaint vigorously."