A teenage boy has been assaulted in a noxious substance attack in east London.
Police were called by the London Ambulance Service in the early hours of 30 December following reports that a 17-year-old had been attacked.
The boy told the officers that up to four suspects had approached him as he walked along a street.
A liquid was splashed into his face and he was chased and threatened with knives.
The suspects stole the boy's watch and wallet and it is believed that they fled the crime scene in a Toyota Prius.
The victim was taken to an east London hospital for treatment and has since been discharged.
Detectives are investigating but a lack of CCTV in the area and the fact that the suspects covered their faces have prevented the group's identification.
Officers would like to hear from anyone who was in the area at the time of the assault, or who remembers seeing the car.
No arrests have yet been made and enquiries continue.
The victims were taken to hospital after suffering facial injuries after two groups were reportedly involved in a fight near the crime scene.
Existing police powers allow officers to stop and search people if they are suspected of possessing a corrosive substance with the “intent of causing injury”.
But people suspected of carrying acid "without good reason" could soon be stopped and searched by police officers, under enhanced powers suggested by the government in September 2018.
Anyone with information about the Romford attack is asked to call the East Area Command Unit via 101 quoting reference 994/30Dec18
Alternatively, they can call Crimestoppers anonymously on 0800 555 111.