Detectives have released an e-fit image of a man they would like to identify in connection with a stabbing in Ilford on Bank Holiday Monday, 28 May.
Police are also keen to speak with a woman who was in the area at the time of the attack and who may have information that could assist with their enquiries.
The woman is described as white, with red hair. She is also believed to have been walking two dogs of the same breed (unknown), with one of the dogs lighter and one darker in colour.
The suspect is described as an Asian man, aged between 20 and 30 years old. He was wearing a long green jacket and carried an eight-inch silver bladed knife with a brown handle. He is believed to have left in the direction of Perth Road following the attack.
Police were called by the London Ambulance Service (LAS) to Valentines Park on Perth Road in Ilford at 4.28pm on Monday, 28 May to reports of an injured man.
Officers and LAS attended. At the scene, a 28-year-old man was found suffering from stab injuries to his back and neck. He was taken to an east London hospital where his condition was deemed not life-threatening and he has since been discharged.
Officers are also keen to hear from anyone who may have witnessed the incident or who who may have seen the suspect either before of after what appears to have been an unprovoked attack.
Anyone who witnessed this incident but has not yet spoken with officers should call police on 101 quoting reference number CAD5215/28May or tweet @MetCC.
Alternatively, contact the independent charity Crimestoppers anonymously on 0800 555 111.