Police were called at around 4.10am on Saturday, 10 October to Liverpool Grove, SE17 to reports of a rape.
The incident is understood to have taken place at around 3am in the grounds of St Peter’s Church.
Following the attack, the female victim sought assistance from the occupants of a nearby house, and police were called.
Detectives from the Central South Command are investigating.
Detective Constable Jake Good, said: “This was clearly a very serious incident and we are carrying out a number of enquiries to identify the person responsible. I would ask that anyone who saw anything suspicious in the area at around that time to please come forward. Any detail – no matter how small – could assist with our investigation.”
Anyone with information is asked to call 101 and quote Cad 1207/10Oct.