Prince Charles plans to make "heartfelt interventions" in British life when he becomes king, the Guardian newspaper reports, citing sources close to the outspoken heir to the throne.

The prince, who has long courted controversy with what some see as political meddling, will remain "true to his beliefs and contributions," an unnamed source told the newspaper.

"Rather than a complete reinvention to become a monarch in the mould of his mother, the strategy will be to try and continue with his heartfelt interventions, albeit checking each for tone and content to ensure it does not damage the monarchy," the source said.

Members of the royal family by convention do not comment on political affairs, and Queen Elizabeth II is famous for keeping her own counsel.

However, her 66-year-old son Charles has come under criticism in the past for his outspoken remarks about everything from genetically modified food to architecture.

"The prince understands the need to be careful about how he expresses concerns or asks questions, but I do think he will keep doing exactly that," Patrick Holden, an organic farmer and friend of the prince told the Guardian.

"He is part of an evolving monarchy that is changing all the time. He feels these issues are too serious to ignore."

The prince's office, Clarence House, declined to comment on his future intentions.

"Speculation about the Prince of Wales' future role as king has been around for decades but it is not something we have commented on and nor will we do so now," a Clarence House spokeswoman told the Guardian.

"The Prince of Wales cares deeply about this country and has devoted most of his working life to helping individuals and organisations to make a difference for the better - and not for his personal gain."