Clarence House has robustly denied reports that the Prince of Wales believes becoming King would be akin to "prison".
A profile in American weekly magazine Time features a comment from a member of the Royal Household who said Charles, who turns 65 next month, is worried that he will not achieve ambitions linked to his various interests before "the prison shades" close.
The front-page article, The Forgotten Prince, said Charles is keen to continue with as much of his environmental and charitable work as possible before acceding to the throne.
It follows interviews with more than 50 friends, associates and current and former employees.
It is not known whether the comment was made by a current or former member of royal staff.
A Clarence House spokesman said: "This is not the Prince of Wales's view and should not be attributed to him as he did not say these words.
"The Prince has dutifully supported the Queen all his life and his official duties and charitable work have always run in parallel."
The last year has seen Charles, along with other senior members of the Royal Family, take on increasing responsibilities and duties as the Queen scales back her commitments.
Journalist Catherine Mayer, who was given rare access to the Prince, said he was "joylessly" increasing his royal workload as he gears up for his role as King.
She added that he was "impatient to get as much done as possible" ahead of succeeding his mother as monarch.
Ms Mayer said: "Far from itching to assume the crown, he is already feeling its weight and worrying about the impact on the job he has been doing.
"The Queen, at 87, is scaling back her work, and the Prince is taking up the slack, to the potential detriment of his network of charities, initiatives and causes."
Charles is quoted as saying: "I've had this extraordinary feeling, for years and years, ever since I can remember, really, of wanting to heal and make things better.
"I feel more than anything else it's my duty to worry about everybody and their lives in this country, to try and find a way of improving things if I possibly can."
The article also revealed that the Prince staged a dress rehearsal to teach the Duke of Cambridge the intricacies of hosting an investiture - complete with a sword sent from London.
Charles held the trial run for William during a family holiday at Birkhall in Scotland last month.
He taught his son how to dub a new knight with a blade sent from the capital along with Prince George's pram.
His wife, Camilla, and daughter-in-law Kate also stayed at Birkhall.