Police are appealing for any information or witnesses to a sexual assault near New Kent Road on Sunday 14 February.
It happened at about 11.50pm in Balfour Street SE17, towards the New Kent Road end.
The victim was a 23-year-old woman who was approached suddenly by a man who dragged her into a doorway and sexually assaulted her. He then ran away in the direction of New Kent Road. She did not know her attacker.
Two passers-by came to her assistance on the street.
The suspect is described as white, possibly in his mid 20s, of slim build and about 5ft 4ins tall. He was wearing a hooded jacket but the victim remembers he had a very pointed nose.
The incident is being investigated by the Sapphire Unit based at Walworth.
"Although it was late at night, this is a busy part of London and a main bus route and there were quite a few people around," says Detective Constable Richard Huggins.
"I am appealing for anyone who may have seen anything of the incident or maybe saw a man of this description in the area."
Officers are investigating whether the incident was captured on CCTV cameras in the area.
Anyone with any information should call the unit on 020 7232 6182 or Crimestoppers on 0800 555 111 to remain anonymous.