CCTV footage has been released by police investigating a violent knife attack in Northolt .
The incident left the victim, a 21-year-old man, with a deep cut across the left side of his face.
Police were called to Shadwell Drive just before 6.30pm on May 1 to reports of a serious assault outside a property.
The victim was standing on the road when he was approached by a group of men on bicycles. He was slashed across the face by one of the gang before they rode off.
He was taken to an east London hospital where he needed stitches for his wound.
Police have now issued CCTV taken from a nearby address which appears to capture the moment of attack.
The suspect is a black man wearing blue jeans, a blue jumper and a black jacket.
Anyone with any information is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.