Daniel Radcliffe came to the aid of a tourist who was targeted by thieves in London, according to an eyewitness.
The Harry Potter star was one of a number of people who went to assist the man who, according to police, suffered a cut to the face during the incident.
The man, aged in his 50s, was attacked by two people on a moped who snatched his bag before riding off.
Witness David Videcette said Radcliffe had consoled the victim and identified himself upon request.
“He was walking on the street and witnessed it too,” Mr Videcette told the BBC.
“A lot of people – especially in his position – wouldn’t have stepped in to help, so fair play to him.”
Mr Videcette, a former Metropolitan Police detective who now writes crime novels, said he had seen the moped riders acting suspiciously before they struck.
“I was driving through Chelsea and noticed a motorcycle with no number plates on it,” he said.
“It was cruising down the road and they didn’t look like they were travelling to go somewhere – they were looking around at people on the road.”
Mr Videcette said one of the riders dismounted and attacked a man carrying a Louis Vuitton bag.
“The man was a tourist visiting England for a few days and he was very shaken,” he told the BBC.
“He had a facial wound which was bleeding – he said he’d been slashed with a knife.”
Mr Videcette said he had unsuccessfully attempted to ram and follow the moped before returning to the scene and encountering Radcliffe.
Radcliffe’s spokeswoman confirmed the 27-year-old was present but made no further comment about the incident, which took place on Friday evening and was first reported in the Evening Standard.
Earlier this year it was reported that actor Tom Hardy helped to apprehend a man who had allegedly stolen a motorbike in Richmond in south-west London.
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