A man has been taken to hospital after being doused with a liquid during a suspected attempted robbery near London's Harrods department store.
Scotland Yard said it was called at 8.33pm on Monday to reports of an assault in Walton Place, Knightsbridge, where "men on a moped" had thrown liquid in a pedestrian's face.
The victim, a 47-year-old man, was treated by paramedics at the scene before being taken to a central London hospital.
The extent of the man's injuries has not been disclosed, however police said they are not thought to be life-threatening.
Scotland Yard said it is not known if the liquid was a corrosive substance.
A spokesman said: "Officers from Kensington & Chelsea Borough are investigating, and at this early stage it is believed the liquid was thrown at the victim during an attempted robbery."
The force said no arrests had been made at this stage and appealed for witnesses or anyone with any information to come forward.
The incident follows a recent spike in the number of attacks involving corrosive substances.
More than 400 were carried out in the six months up to April 2017, according to figures from 39 forces in England and Wales.
The Metropolitan Police has said its response cars will now carry equipment that will help officers to better deal with calls to such attacks.
To give information anonymously, witnesses to Monday's attack are urged to call Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.