British tabloids The Daily Mail and The Daily Express published pictures Thursday of the two royal ladies emerging from a top London hotel. The reports said the two women met for lunch to discuss Middleton's April 29 wedding to Prince William at Westminster Abbey in London.
Camilla, the Duchess of Cornwall, is the 63-year-old wife of Prince Charles, William's father.
The Mail quoted an unidentified fellow diner as saying he overheard Camilla saying "if I can give you one bit of advice."
Palace authorities were not immediately available to comment on the reports.