Detectives are investigating a string of violent daytime robberies of women around Elephant & Castle and Walworth during September.
The first incident took place on Monday 7 September at approximately 4pm in Tiverton Street, SE1.
The victim, a 46-year-old woman, was walking with her young son when she was approached and grabbed from behind by the suspects. A gold necklace with a heart pendant was snatched from the victim's neck.
The second incident took place a short while later at approximately 6pm in Olney Road SE17. The victim, a 70-year-old woman, was walking home alone when she was grabbed from behind by her head. The suspects snatched the gold chain from around her neck and pushed her to the floor.
Incident three happened on Wednesday 9 September at approximately 1pm in Sturgeon Close SE17. The victim, a 37-year-old woman, was walking home with her young son. The suspects snatched her mobile phone out of her hand, and then grabbed a gold chain from around her neck, before running off.
The final robbery took place on Tuesday 29 September at approximately 12.15pm in Andrews Walk SE17. The victim, an 85-year-old woman, was walking home alone when she was grabbed from behind by her face and her gold chain snatched from around her neck.
None of the victims received serious injuries.
Suspect A is described as a black male, aged 16-18, between 5ft 8ins and 5ft 10ins in height.
Suspect B is described as a black male, aged 16-18, between 5ft 8ins and 5ft 10ins in height.
Officers would like to speak with anyone who witnessed any of the robberies.
Detective Constable Stefan Yiannaki, from Southwark CID, said: "This is a sickening series of robberies of vulnerable victims.
"I would urge anyone who has information about the two males involved, or who can help assist with our investigation, to call police. All calls will be treated in the strictest confidence."
Anyone with information is asked to contact police via 101.