The Government has unveiled an £8 million fund for schools, councils, courts, police and fire stations to receive a free portrait of the King.
Public institutions across the UK will be entitled to claim one official framed photograph of His Majesty as part of the coronation celebrations next month.
To mark the new reign, the Chancellor of the Duchy of Lancaster, Oliver Dowden, said the portrait would “serve as a visible reminder in buildings up and down the country of the nation’s ultimate public servant.”
He added: “They will help us turn a page in our history together and pay a fitting tribute to our new sovereign.
“I am sure they will take pride of place in public buildings across the land.”
But the move was attacked by anti-monarchy campaigners – who accused the Government of wasting money that could be better spent on public services.
Graham Smith of campaign group Republic said: “This is a shameful waste of money. At a time when a majority of local councils are raising taxes and cutting public services, when schools and hospitals are struggling, to spend even £1 on this nonsense would be £1 too much.
“Charles dodged a huge tax bill last year, when he inherited an estimated £650 million from the Queen. Surely if anyone really wants an official portrait he can stump up the cost himself?
“The Government has lost the plot if they think people want their money spent on pictures of Charles. They need to scrap this scheme and direct the money where it’s really needed.
“The coronation is estimated to cost anything from £50-£100 million – and we can see why. This waste is absolutely scandalous.”
The scheme to request a portrait, yet to be unveiled, will open later this year after the coronation, which takes place on 6 May.
Chief Secretary to the Treasury John Glen said: “This scheme will allow thousands of public institutions across the UK to mark this defining moment in our nation’s history with pride.
“The coronation of His Majesty the King is an opportunity for the whole country to unite, and these new portraits continue a very British tradition to celebrate this momentous occasion.”
Official portraits of Queen Elizabeth II are currently on display in many public institutions, and the offering of the new official portrait of King Charles III will enable organisations across the UK to carry on that tradition, the Cabinet Office said.