A thief has stolen an ambulance service bike while the paramedic was in an office block treating a patient.
The "despicable" crime happened at around 2.40pm on June 23 in the City of London when the bicycle was parked outside offices in Minories.
Detective Constable Dave Hughes said: "This is an absolutely despicable theft from a paramedic who was simply doing their job, travelling across the capital doing vital work helping people in need.
"If you have any information which can help us find the person responsible and return the bike, we urge you to get in touch."
City of London Police issued a picture of the suspect, who is white with short, fair hair and was wearing a blue quilted jacket over a purple T-shirt.
London Ambulance Service Cycle Response Unit manager Tom Lynch said: "It's shocking that someone would steal from a paramedic who was busy treating a patient. This causes a lot of disruption to our service as there was a delay before they were able to get back out on duty.
"Our paramedics should be able to focus solely on their patients and not have to worry about someone stealing their equipment."
Anyone with information can call City of London Police on 0207 601 2999 or Crimestoppers anonymously on 0800 555 111.