Royal watchers were sent into a spin this week when a file purporting to contain a copy of the prince's best man speech and an associated presentation were posted on a website.
It has since emerged the information had been leaked by a student on work placement at marketing company Article 10 Presentations, and bosses have now spoken out to apologise to Prince Harry.
In a statement, a spokesman for Article 10 says, "On Tuesday April 19, Article 10 Presentations became aware of a leak of confidential and sensitive information relating to a project undertaken for Prince Harry which, regrettably, has since attracted significant attention online."
"Article 10 Presentations would like to sincerely apologise to Prince Harry and the royal family and is working with the authorities to remove (the) website and associated content from YouTube.com. Article 10 Presentations takes breaches of customer information very seriously and has since dismissed the placement student responsible for the leak and is considering further disciplinary action."
"Prince Harry's best man speech and supporting presentation was hosted on a confidential page of the Article10 Presentations website. This was shared with a third party who posted the link on their Twitter feed. Article10 management has apologised personally to Prince Harry and will be launching a full investigation in to the matter, implementing tighter security measures as a result of this incident."
Prince William is due to wed Kate Middleton in London on April 29. Prince Harry will undertake best man duties on the day.