Prince William and Kate Middleton aggressively pursued in their car by the paparazzi

The Prince was left concerned by the threatening behaviour, his spokesman Paddy Harverson, said.

The couple, who have rekindled their relationship after splitting up earlier this year, were leaving London's Boujis nightclub in the early hours of Friday morning.

Mr Harverson said: "Prince William was concerned by the threatening behaviour of the paparazzi. Having already been photographed leaving the club, he and Kate Middleton were then pursued in his car by photographers on motorcycles, in vehicles and on foot.

"The aggressive pursuit was potentially dangerous and worrying for them. It seems incomprehensible, particularly at this time, that this behaviour is still going on."

The incident happened in a week which saw the start of the inquest into the death of the Prince's mother, Diana, Princess of Wales, whose car crashed in Paris in 1997 as she was being followed by photographers.