Dramatic footage has emerged which appears to show a policeman attacking a car after the driver refuses to get out.
The clip, shared on social media on Saturday and viewed more than 40,000 times, shows what appears to be a police officer - filmed from the position of the driver - repeatedly telling him to "get out of the car", adding: "You're not allowed to drive it."
The officer then hits the driver's side window with what looks like a baton, before a voice can be heard saying: "I've got a licence. I've got a licence. I've got insurance. You're smashing this for no reason."
The policeman can be seen striking the windscreen, resulting in the glass shattering, and he then starts slicing around the damaged area with what looks like a pen knife.
When asked by the driver what the problem is, the officer tells him he is "not allowed to drive".
The video, which could not be independently verified, has been shared on Twitter and Instagram where the officer's actions have been described as "mindless vandalism and intimidation".
A man who wanted to be referred to by just his first name, Leon, told the Press Association he was the driver and the person who filmed the footage.
He said the incident took place on Friday evening in the Gospel Oak area of north London, and said it was a case of "mistaken identity", describing the officer's actions as "a completely unlawful act".
When contacted about the footage, the police force said on Saturday evening: "As soon as the MPS was made aware of the footage, the DPS was contacted immediately. The individual who uploaded the footage has been contacted by DPS officers.
"As this matter is in its early stages, the officers have not been suspended or placed on restricted duties. No-one was arrested during the incident."
Leon, who said he spent the evening in hospital due to getting glass in his eyes, said it was "complete madness" and that he is "still in shock".
"Every time he smashed the glass, fragments of glass were just ricocheting in my face," he said.