FORMER Manchester United star Cristiano Ronaldo faces a police probe after kicking in a car window.

The 24-year-old says he 'regrets' what he did but insists he was protecting his mother, Dolores, from harassment by a paparazzi photographer.

He was in Lisbon in his homeland Portugal when he became involved in a confrontation with Sara Pardal, 17, as he made his way to an Elton John concert with his mother.

Ms Pardal was reportedly treated in hospital for cuts following the incident and has complained to local police after the footballer jumped out of his Ferrari and kicked the side window, sending glass into the vehicle.

It is believed she was with a freelance photographer when the incident happened on Sunday, although she has reportedly insisted she was filming him as a fan.

Ronaldo was signed by Real Madrid for £80m last month and is due to be unveiled to their fans next week.

He said in a statement: "When I'm on my own, fine. I try to swallow it and remain indifferent. But when my mother is involved, then I'm sorry but I don't let anyone, I repeat anyone, harass her.

"I regret what I did. But I can't promise that I would not react in the same way again in the same circumstances because when my mother is involved it is very difficult for me to keep a calm state of mind."

He continued: "The incident involved an individual who unfortunately does not care what he does to achieve his aims, who I have seen standing for days on end in front of my house, eating yoghurts and holding a camera in his hand, waiting for anything newsworthy to happen, and who due to frustration and boredom changed his strategy.

"He chased me from the car outside the Ritz Hotel to the Expo area, which is where my apartment is. I was accompanied by my mother, and he by a young woman who throughout our whole journey ostensibly and provocatively filmed all our movements.

"This persecution caused my mother to be so disturbed and upset that I had to stop my car to try to convince them to leave us in peace."

Ronaldo said he kicked the car when his plea for him and his mother to be left alone was ignored.

The world player of the year also alleged efforts were made to sell him a video which captured the incident. He said: "I could never, I emphasis, never, agree to a proposal."

He insisted the girl in the car had no 'visible injury' and appeared to be wearing a hospital gown at the time.

Ronaldo also lamented that there were 'always unscrupulous buyers' willing to purchase such footage and he expected it to be made public.

"That's not my way. I could have bought the tape and the subject would never have been made public. But I know it will be made public. Because that's what I want, because this is the only way I know how to be in life", he said.