Buckingham Palace has written to the press watchdog to register a complaint over claims that the Queen voiced strong Eurosceptic views during a lunch with the former deputy prime minister.
The Sun said she vented her anger with Brussels at the pro-EU Nick Clegg during a lunch at Windsor Castle in 2011.
A Buckingham Palace spokesman said: "We can confirm that we have this morning written to the chairman of the Independent Press Standards Organisation to register a complaint about the front page story in today's Sun newspaper.
"The complaint relates to Clause One of the Editors' Code of Practice."