Royal officials are denying widespread and persistent rumours that Prince William will announce his engagement to long-time girlfriend Kate Middleton at the beginning of June.

Prince William walks with his longtime girlfriend Kate Middleton at RAF Cranwell, in central England, in 2008. (Michael Dunlea/Reuters)

The rumour started on Monday, when writer/blogger Tina Brown wrote on The Daily Beast website that "a highly placed source in royal circles said that two days in June have been mysteriously blocked out on the palace diaries — June 3 and 4" and suggested those are likely dates for "an engagement announcement."

"If June were indeed to be the announcement date, a wedding itself would probably follow in November," Brown continued, before suggesting that a December announcement and June 2011 wedding are equally possible.

Speculation soared as British newspapers and websites picked up the story.

The buzz fizzled slightly a day later, when the prince's official residence refused to comment on what it termed "speculation."

"We don't comment on speculation," a Clarence House spokesman told CNN.

Prince William and his father, Prince Charles, have public engagements on June 3 and 4, while the Queen has an official engagement on June 3, the Daily Telegraph's website quoted a Clarence House spokesman as saying.

Dom Perignon, bookies weigh in

But the rumour has yet to die down altogether.

Bosses at Dom Perignon headquarters in France have confirmed 300 vintage bottles of champagne from the Queen's private collection are ready to be shipped to Britain and bookies have slashed odds on a summer engagement, London's Daily News reported Thursday.

Prince William, 27, and Middleton, 28, have dated on and off for seven years. They met as students at St. Andrews University in Fife, Scotland, in 2002.

William is the older son of Prince Charles and Diana, Princess of Wales, who died in 1997.

Brown is the author of the best-selling The Diana Chronicles, a detailed biography of Diana published in 2007.