A wealthy property investor who will need reconstructive surgery on his face after a violent roadside robbery fears someone will be killed if police do not catch the gang responsible soon.

The 54-year-old, who does not wish to be named for fear of reprisals, was punched in the face with a weapon, believed to be a hammer, before being robbed of his £8,000 Rolex watch after parking his Porsche 911 in a South Hampstead street last Thursday.

It follows a string of violent jewellery muggings on Hampstead streets stretching back to May this year - and marks a significant escalation in the level of violence used.

The victim of last week’s attack, which involved three men on motorbikes, was left with a deep wound to his face and a fractured cheekbone.

He said: “They hit me before they demanded the watch, so this is gratuitous violence. This guy [who hit me] will end up killing someone. He is extremely dangerous, it’s like having a wolf roaming the streets.”

The father-of-three was approached by two men on a motorbike and another man on a moped, who were all wearing helmets, as he got out of his parked car last Thursday at 6.30pm.

Before he had a chance to speak, he believes one of the suspects, a white man, punched him in the face with the end of a hammer which he then started swinging above his head as he demanded the man’s Rolex.

“I bent down to pick up my papers and there was blood dripping on them,” he said. “I literally had a hole in my face. What really concerns me is if I had made any effort to resist he would have landed that hammer on my head and killed me.

“The police tell me there’s a gang of four to six who are going around doing this. The public should be made aware. Anybody who has a high-value car is going to be targeted. Anyone with a Porsche or Ferrari is going to be followed home.”

Last week, a woman living in Aberdare Gardens, South Hampstead, was violently robbed of her handbag after parking her car outside her home.

The two attackers, believed to have followed the victim home, got into a car and sped away.

Insp Howard Hornby, of Camden Police’s North Neighbourhood Policing Team, said officers do not believe the South Hampstead incidents are linked.

But he could not rule out links between the hammer attack last week and similar robberies in Hampstead in May, July and September this year.

He said: “The hammer attack is horrific, it really is. It’s a nasty, nasty crime that doesn’t really happen here.

“I can assure the public that we are continuing with high-visibility patrols in an attempt to disrupt and disperse it.”

Anyone with information should call Camden Police on 101. Alternatively, if you wish to remain anonymous call Crimestoppers on 0800 555 111.