It should have been an easy PR opportunity for Spain’s Royal household, which normally has little to fear from the country’s media, when the Zarzuela Palace — the equivalent of Buckingham Palace — decided to mark Prince Felipe’s promotion to lieutenant-colonel with a series of portraits of the heir to the throne in dress uniform.

But instead of the usual slavish media coverage, the Royal Family found itself facing unwelcome questions about whether the Prince was the latest figure to have his image changed using photo-manipulation software.

In the pictures, his uniforms are different but his face is uncannily similar — so much so that the daily El Mundo newspaper was suspicious and subjected them to further scrutiny.

When the newspaper superimposed all three photographs on top of each other, staff detected small differences in the way the Prince posed for each portrait.

Yet, they claimed, the face was exactly the same in each photograph.

Their conclusion: Dany Virgili, the photographer, had used different poses of the Prince in uniform, but, with software, had superimposed the same image of his head on each.

The right-wing newspaper, which normally offers largely uncritical coverage of the Royal Family, was swift to condemn the apparently hamfisted publicity exercise.

“It is not something of great importance, but it is something that should not have happened,” it said in a leading article yesterday.

“It gives the idea of a virtual monarchy which can’t be taken seriously.”

Mr Virgili and the Palace were swift to deny the claims.

The photographer said: “In the one of the Air Force [the Prince] has his head turned more to the left, and in the one of the Army, his chin is more elevated.” The Palace told The Times: “There is no question of Photoshop being used.”

The controversy has marred what the Spanish Royal household no doubt hoped would be a chance to promote the future King and Queen.

The series of portraits also included pictures of Prince Felipe and Princess Letizia together, but these failed to attract the normally doting attention which any new images of the princess usually receives from the Spanish media.

Variety magazine was recently allowed rare access to the Royal couple in what was seen in Spain as an attempt to promote the future monarchs as they prepare to succede King Juan Carlos, who is 71.

The row over the pictures comes five years after a PR bungle in which the Palace published Christmas photographs of King Juan Carlos and Queen Sofia with their grandchildren.

The exercise quickly backfired after it emerged King Juan Carlos appeared not to have any legs and his image had been superimposed into the photograph because he could not make it to the photo shoot.