This is the shocking moment a woman was punched in the head while she waited to cross the road at a crossing in south London.

Video footage shows the victim, 25, waiting at traffic lights on busy Clapham High Street when a stranger runs at her from out of nowhere and hits her in the head.

The man smashes his fist into the side of her face before running off to the other side of the street.

The terrified victim is thrown forward and stumbles as she tries to get away, while passers-by stop to help.

The injured woman flagged down police officers who searched the area, but the suspect had fled after making off towards Gauden Road.

Detective Constable Dan Nash, from Lambeth CID, said: "The victim was simply going about her business when out of the blue a man approached her from behind and punched her in the side of her head before running off.

"This was an unprovoked attack which has left the victim very distressed. CCTV footage shows the man loitering at the location for a few minutes before the attack.

"Clapham High Street was very busy at the time of the incident. Someone must have seen something, so I am appealing for any witnesses or anyone who recognises the man to come forward."

The unprovoked attack happened at just before 7.30am on Wednesday, September 14.

Detectives in Lambeth have released CCTV footage of the man they would like to speak to. The suspect is described as a black man, aged between 30 and 40 years, 6ft tall and with shorth black hair.

He was clean shaven or had short stubble and was wearing dark trousers and a green jacket, police said.

No one has yet been arrested and enquiries continue.

Anyone with information can call police on 101 or Crimestoppers anonymously on 0800 555 111.