A man has been charged after allegedly posing as a police officer and demanding the occupants of a car hand him their vehicle - not realising it was an unmarked police car.
Scotland Yard said the alleged incident happened outside a Waitrose supermarket on Ballards Lane in Finchley, north London, in the early hours of Thursday morning. Plain-clothed police officers were on patrol in the area.
A force spokesman said: "Allegedly a man stepped on to the pavement, into the way of the car, flagged it down and said: 'Give me your car, I'm a police officer.'
"They declined to acquiesce and the driver identified himself as a police officer. The incident ended up with a man being arrested and subsequently charged."
It is claimed there was an altercation while the arrest took place.
A 22-year-old from the Friern Barnet area was charged with interfering with a motor vehicle and two counts of assault on police officers and will appear at Hendon Magistrates' Court on 1 May.