Two men demanded $100,000 from a member of the British royal family to hand over video and audio recordings containing "scandalous and disparaging" allegations against him and other royals, prosecutors said Tuesday.

Prosecutor Mark Ellison said one audio recording included a royal aide "apparently asserting that the member of the royal family who employed him had performed an act of oral sex on him."

Ian Strachan, 31, and Sean McGuigan, 41, are on trial at London's Central Criminal Court charged with attempted blackmail. A court order bars journalists from identifying the victim or any witnesses in the case.

The royal was identified in court only as Witness A.

Ellison told the jury that Strachan and McGuigan claimed they were not motivated by money but were acting out of concern for the royal's reputation. But he said they tried to sell the material on the recordings to British newspapers for as much as $400,000.

When the newspapers declined to pay, the men approached the royal seeking money in return for handing over the recordings, Ellison said.

The prosecutor said that while McGuigan in particular was coy about discussing money, "when you consider what they each said and did as a whole ... the evidence proves that they were both together engaged in blackmail."

Buckingham Palace has refused to comment on the case, but British media have reported that the blackmail target was not a senior member of the royal family.

Ellison said Strachan and McGuigan were initially motivated by strong dislike of the royal aide, identified as Witness D. They covertly recorded eight hours of audio and video footage of him, much of it on a mobile phone.

In addition to the sex claim, the footage shows Witness D apparently taking drugs — at one point allegedly using a credit card to cut lines of cocaine — and making "various disparaging remarks about various members of the royal family," Ellison said.

Ellison said the aide also made "allegations of impropriety as to how his employer conducted aspects of his business."

Prosecutors say that, in the summer of 2007, after failing to sell their story to a newspaper, the defendants attempted to set up a meeting with the royal to hand over the tapes in return for money.

Amid the negotiations, the Metropolitan Police force was called in by the royal and his staff.

Strachan claimed in a conversation recorded by police that some of the material on the tapes "was very graphic and goes into a lot of detail."

He and McGuigan were arrested Sept. 11 in a police sting operation at a London hotel. An undercover detective posing as a royal aide contacted the alleged blackmailers and arranged the meeting at the London Hilton.

If convicted, the defendants face a maximum sentence of 14 years in prison.

The trial is expected to last a month.