Prince Charles's lawyers warned editors that publication of Vegas photos abroad was no excuse for printing them in UK

Prince Charles's royal aides threatened legal action against newspapers if they published photographs of Prince Harry naked in a Las Vegas hotel room, despite the fact they were freely available on the internet.

Lawyers at Harbottle & Lewis, the London legal firm, swung into action on Wednesday after they were notified by St James's Palace that a number of British newspapers had expressed an interest in buying the photographs and had intended to publish.

The photographs were being sold for £10,000 by the Splash News picture agency and it is understood about 10 British and Irish titles expressed an interest in buying them. So far no British titles have published the pictures, either in print or online, but three Irish titles have done so.

Newspaper editors are understood to have been asked informally by royal aides not to run the pictures at lunchtime on Wednesday. Later in the day a strongly worded letter from Harbottle & Lewis was circulated via the Press Complaints Commission, along with a covering note from the regulator saying it was happy to pass on St James's Palace's view that publication would be in breach of clause three of the PCC's editors' code of practice. The clause says "it is unacceptable to photograph individuals in private places without their consent".

The letter from Harbottle & Lewis warns editors that publication outside the UK is no justification for publication in Britain.

"The only possible reason for publication of the photographs is one of prurience and nothing more," said the letter from the law firm.

"No matter of public interest as those words are understood in English law is raised by these photographs. The fact that they have appeared in another jurisdiction is meaningless."

The letter ended by warning that the members of the royal family "entirely reserve their rights as to any further steps" should publication occur.

No British paper published the photos although the Irish edition of the Daily Star put them on the front page. Daily Star proprietor Richard Desmond has removed all his papers from the PCC regime, but the title is understood to have made a decision not to publish in Britain.

Neil Wallis, former executive editor of the News of the World, said the decision by UK tabloids not to publish the photos demonstrated the "chilling effect" the Leveson inquiry was having on papers.

In a blog on the Huffington Post he said Lord Justice Leveson had "neutered the great British press and made it a laughing stock".

However, Peter Willis, editor (weekday) of the Daily Mirror. said that, on the contrary, the decision showed self-regulation was working.

"We are constantly told the PCC is a toothless tiger and this shows that it is not. We don't want PCC judgments against us. We drafted the code and we signed up to it," he said.

In its coverage of the affair on Thursday, the Daily Mail points out the pictures were "banned in Britain – but the pictures can be seen worldwide", listing more than 100 websites, newspapers and other news organisations, including US broadcasters CNN and CBS, which published the photos.

Daily Mail executives have been among the most forthright voices at the Leveson inquiry warning that foreign publication on the internet risked undermining UK press regulation.

Ian Mallon, deputy editor of the Evening Herald in Ireland, which used the pictures, said the brouhaha over privacy was just a "nonsense" and said British newspapers had been cowed into censorship for all the wrong reasons.

"Prince Harry obviously didn't mind being photographed ... The big thing now is the fear factor that comes from London and editors who are absolutely petrified to be seen to be doing something untoward," Mallon added, referring to the prospect of Leveson recommending the abolition of self-regulation of the British press.

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