Two men tried to blackmail a member of the royal family with an audio recording featuring claims that he had performed a gay sex act at a party, a court was told on Tuesday.

Ian Strachan, 31, and Sean McGuigan, 41, are alleged to have tried to blackmail the royal, who cannot be identified, out of 50,000 pounds after failing to sell the story to a number of national newspapers.

Both deny making an unwarranted demand with menaces.

The recordings at the centre of the claims contained material from a man employed in the royal household which, if ever published, would have the potential to "cause embarrassment and hurt to his employer", said Mark Ellison, prosecuting.

The recordings also contained "scandalous and disparaging remarks" about other royals, the jury at the Old Bailey was told.

The court heard that in early 2007, Strachan and McGuigan made a series of audio and video recordings of "witness D" - the man employed by the royal - apparently asserting that the member of the extended royal family had performed an act of oral sex on him.

Strachan made the recordings of witness D on McGuigan's mobile phone and then downloaded them on to his computer, the court heard.

Much of the eight hours-worth of files was recorded when witness D, "for whom they have professed a strong dislike", and who had been employed for many years by the royal, was drunk or "under the influence of other substances", the court heard.

"He was also shown recounting stories and alleged experiences, making allegations of impropriety as to how his employer conducted aspects of his business," Ellison said.

The man was heard giving forthright opinions "on a wide range of other members of the royal family - which included a number of scandalous and disparaging remarks"," said the prosecutor.

Between March and July 2007, Strachan allegedly approached newspapers - The News of the World, The Sun, the Sunday Express, Mail on Sunday - and publicist Max Clifford to try and sell the material, asking for a "substantial sum".

But by July 2007, he had not managed to sell the story, the court heard.

Strachan and McGuigan then allegedly turned their attention from the media to the royal - witness A.