Prince Harry was involved in a scuffle outside a nightclub early today which left a photographer with a cut lip.
Clarence House said the 20-year-old royal pushed back after he was hit in the face by a camera outside the Pangaea club in the West End of London.
But the photographer claimed the prince "deliberately lashed out".
Another witness said the prince was swearing during the altercation and buried his head in his knees afterwards as his car sped away.
But a Clarence House spokesman said the third in line to the throne was defending himself when the incident happened at around 3am.
"Prince Harry was hit in the face by a camera as photographers crowded around him as he was getting into a car," the spokesman said.
"In pushing the camera away, it's understood that a photographer's lip was cut."
Chris Uncle, the paparazzi photographer involved, gave a different version of events.
Mr Uncle, 24, told a London's Evening Standard reporter that he reported the incident to police shortly afterwards and was considering whether to make a formal complaint.
Mr Uncle, who works for the Big Pictures agency said: "Prince Harry looked like he was inside the car and we were all still taking pictures.
"Then suddenly he burst out the car and lunged towards me as I was still taking pictures.
"He lashed out and then deliberately pushed my camera into my face. The base of the camera struck me and cut my bottom lip. At the same time he was repeatedly saying 'Why are you doing this? Why don't you just leave me alone?' "
Mr Uncle claimed the prince's protection officers pulled the royal off and pushed him back into the car.
Big Pictures said the agency did not wish to comment about the incident.
But another photographer who was outside the club said the prince had no reason to react as he did.
"In this situation he wasn't under any threat. The photographer who he went for is the mildest mannered photographer," he said.
A Scotland Yard spokesman said: "We are aware of the incident but no complaint has been made."
The incident comes just a week after new army recruit Harry was accused of cheating in his art A-Level exam.
He is believed to have been upset by claims by sacked Eton art mistress Sarah Forsyth that she helped him pass one of the A-levels he needed to get into the elite Sandhurst military academy, where discipline is paramount.
Miss Forsyth's lawyers revealed that she had secretly recorded a conversation with the prince in which she claimed he admitted he had done little work on some coursework.
Clarence House described the claims, reported extensively in the media, as "incredibly unfair".
Prince Harry and his older brother William have an uneasy relationship with paparazzi photographers.
Their mother Diana died after being pursued by photographers through the streets of Paris in 1997.
Harry's image as a playboy prince has caused concern in royal circles.
But a summer PR offensive showed a more positive side of the prince as he featured in a TV documentary in Africa caring for young Aids victims.
More recently he was pictured coaching young rugby players in the UK.
Harry is said to be staying with friends today at an undisclosed location.
Recently, the Prince opened up to the media in a way never seen before when he recorded the documentary about his gap year stay in the southern African country of Lesotho.
He spoke at length about his mother Diana, Princess of Wales on television for the first time, describing how he was determined to follow in her footsteps by working for charities.
During his schooldays, Harry was relatively sheltered from exposure to the media through an informal agreement in the wake of their mother's death in 1997 for photographers to leave him and his brother William alone while they finish their education.