Daniel Radcliffe, pictured, came to the aid of a tourist who was mugged and cut in the face by a pair of thugs on a moped in London

Harry Potter star Daniel Radcliffe rushed to help a tourist who was slashed across the face by a pair of thugs riding a moped.

The actor, 27, was among a group of people who ran to help the victim – aged in his 50s- after the attack in Chelsea.

The victim – who was only in the UK for a short holiday - had been targeted for his Louis Vuitton bag, which the muggers made off with after cutting his face with a knife.

It is the latest in a spate of incidents involving criminals riding mopeds following five linked acid attacks in east London last week.

Witness David Videcette, a former policeman who worked with the Met Police's counter-terror unit, said he saw the incident unfold from his car and tried to intervene.

He told the Evening Standard: 'They grappled with him [the victim] on the pavement. He wasn't going to give up the bag willingly. I tried to ram the bike with my car but I wasn't able to.

'They slashed him in the face with the knife and made off down the King's Road. I tried to follow them but I lost them as they were jumping red lights.'

Mr Vidicette told the paper he noticed the moped because it did not have a number plate and was 'cruising' along the street looking at pedestrians.

He said he called the police moments before one of the riders pulled out a knife and launched the attack.

Mr Vidicette added seeing a Hollywood actor helping out was a 'surreal moment'.

He told the Standard: 'He was a really nice bloke, a lot of stars wouldn't have stopped to help. The victim was very, very shaken up.'

The attack took place in Hortensia Road, Chelsea, and the thugs made off with a Louis Vuitton bag

A spokesman for the Met Police said: 'Police were called at approximately 6.10pm on Friday, July 14 to reports of a robbery in Hortensia Road.

'The victim - a man aged in his 50s - was walking in the road when two people riding a moped snatched his bag before riding off. The victim suffered a cut to the face during the incident.

'Officers from Kensington and Chelsea investigate. There have been no arrests made and inquiries continue.'

A spokesperson for Radcliffe said he was not commenting on the incident.