LONDON -- Britain's Prince William has broken up with his longtime girlfriend Kate Middleton after a romance conducted under the full glare of the media spotlight.

Prince William (L) and his girlfriend Kate Middleton react as England's Jason Robinson scores the first try during their Six Nations international rugby union match against Italy at Twickenham in London February 10, 2007. [Reuters]

The Sun newspaper broke the surprise news on Saturday and friends of the second in line to the throne confirmed the tabloid story was correct.

An official spokesman for William, eldest son of the late Princess Diana, said only: "We do not discuss his private life."

Middleton, the eldest child of middle-class entrepreneurs who had won plaudits for her fashionable dress sense and poise, was widely tipped to be Britain's next Queen.

She was pursued everywhere by paparazzi photographers -- as Princess Diana was.

The Sun said that the couple, who met while studying at St Andrews University in Scotland, had reached "an amicable agreement" to end their relationship.

The young couple -- he is 24 and she is 25 -- were seen hugging and kissing during a skiing holiday in Switzerland only last month.

The Sun said their relationship had been strained since William graduated from Sandhurst military academy last December at a ceremony attended by Middleton.

William is pursuing his career as an army officer. His younger brother, Prince Harry, also graduated from Sandhurst and is due to join frontline troops in Iraq next month.

A close friend of the couple told the paper: "As far as Kate is concerned, William simply hasn't been paying her enough attention.

"She is stuck in London while he is living in an officer's mess. Kate feels hugely frustrated that their relationship just seems to be going backwards at a rate of knots."

Last month the Sun published a photo of William with an 18-year-old Brazilian student in a nightclub and said he had invited another girl back to his barracks for a nightcap.

Media glare

Some commentators said the constant media glare may have become too much for Kate, who filed a harassment complaint with Britain's press watchdog last month.

"This relationship formed in a media-free zone (at university) but of course since then Kate has been under intense pressure from paparazzi photographers," Arthur Edwards, a Sun photographer, told the BBC. "She really was at her wits end."

As students, William and Kate shared a house. From there, romance blossomed. She is widely recognised as being the one who persuaded the prince to stay on and complete his studies.

Royalty-obsessed tabloids were always convinced she would one day be Queen Kate. The royal family had very much accepted her in the inner circle of what they call "The Firm".

Judy Wade, royal correspondent for Hello Magazine, told Reuters: "I am totally shocked. We were all convinced they were going to get married. She and William had so much more in common than Charles and Diana ever did."

"Maybe she realised the awful burden she would have been under. It's a life sentence marrying a royal."

Comparisons with William's late mother, who died in a Paris car crash in 1997, were inevitable.

Diana had been totally unprepared for the media glare and her husband, heir-to-the-throne Prince Charles, was reported to have felt he was rushed into their doomed marriage.