Complaint: Actor Juan Pablo di Pace claims his manhood was shrunk in an advert to promote an opera

So when Juan Pablo di Pace was asked to appear naked in an advert for the opera in which he was performing, he was only too happy to oblige.

But seven years on, with the poster of di Pace still being used to promote the Royal Opera House's production of Verdi's Rigoletto, the now-established actor has had an attack of the blushes.

He claims a crucial part of his anatomy has been air-brushed unflatteringly, making it appear much smaller than it is in real life.

In fact, the opera house has been accused of "shrinking" his manhood so much in a 2005 version of the poster that it "made it look like he barely had one at all".

As a result of the complaints made by 28-year-old di Pace's lawyers, who also claimed he had not been paid for use of the image, the Royal Opera House has agreed to stop using the poster.

It will create a new advertisement when the production is staged next, in 2009.

The affair started when di Pace was in the chorus line of the production in 2001.

He agreed to pose for the publicity shot, in which he can be seen leaning back against a female actress in one of the opera's main chorus scenes.

So pleased was the opera house with the resulting image that it continued to use it to promote later productions of Rigoletto - including on posters on the London Underground - even though di Pace was no longer taking part in the opera.

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Offending image: The Royal Opera House's picture featuring Juan Pablo di Pace, centre, was shot during the performance of Verdi's Rigoletto, then cropped for billboards and flyers

Since then, di Pace has starred in the successful BBC Scotland soap River City.

He also appeared in the Catherine Tate Show, the film Three with British actress Kelly Brook, and features in this year's Hollywood adaptation of Mamma Mia!.

A friend of the Argentinian actor said last night: "It's hugely embarrassing for a 28-year-old actor for them to plaster his naked body across billboards and buses, doing to his image whatever they wish."

As well as complaining about the unfavourable airbrushing, di Pace has told the opera house that if it is going to continue to use the photograph, he should receive some sort of payment.

Christopher Millard, spokesman for the Royal Opera House, said: "The poster was a generic image of the production.

"Although Juan Pablo was only a member of the chorus, he was used in the centre of this picture to portray the leading role.

"When we begin publicising a show, we don't always have pictures of the lead singer, so it is common for us to use a photograph we have in stock.

"Juan Pablo has been in contact with us through one of his representatives and expressed his discontent and we have agreed that we will no longer be using this particular image."

A spokesman for the actor said di Pace was currently in Argentina, but had been kept up to date with developments.

Rigoletto, an opera in three acts, is considered one of Giuseppe Verdi's masterpieces.

First performed in Venice in 1851, it tells the story of Rigoletto, a bitter hunchbacked jester who seeks vengeance on the Duke of Mantua for seducing his only daughter. But the plan backfires and leads to tragedy.