Detectives from the Met's North East Command Unit are investigating two serious sexual assaults in Newham and Waltham Forest that are linked.
As part of their enquiries officers have released an image of a man they are keen to trace.
In the first incident, police were called on Monday, 1 July at 02:40hrs to a residential street in the Plaistow South area in Newham.
A 35-year-old woman was walking home when she was approached from behind by a man, who then raped her. He also stole property belonging to the victim.
The second incident occurred on Saturday, 6 July at Amethyst Road, Waltham Forest at 04:20hrs; a 31-year-old woman was approached by a man who then raped her. The man also stole property.
Due to the similarities in these attacks, police are treating the incidents as linked.
Detectives would like to speak to the man pictured. The image was captured on a bus in Plaistow shortly before the first incident.
Detective Superintendent Andrew Packer said: "These incidents have been deeply traumatic for the victims, who are being supported by specialist officers. My teams are completing a detailed review of all the facts available so far. In addition to a dedicated investigation team we have extra patrols in the area to provide reassurance and these officers are actively seeking to arrest this suspect.
“Please have a good look at this photo , and let my officers know if you have any idea as to who this man is.
“I would advise any women walking alone at night to remain vigilant, to be mindful of their surroundings, and to keep family and friends informed of where they may be going. If you see anything you think is suspicious, do not hesitate - call 999 immediately."
Anyone who can identify the man is asked to call the investigation team on 07881 330951.
Alternatively call 101 or tweet @MetCC quoting CAD 777/1 July. You can call anonymously on Crimestoppers 0800 555 111