Police have praised a family who went to the aid of a heavily pregnant woman who was assaulted in Reigate.
The woman, aged in her 20s, was walking along Cockshot Hill when police said the “extremely upsetting” incident took place.
A Surrey Police spokeswoman said it is believed the man who carried out the assault was known to the woman.
Detectives from East Surrey Public Protection Investigation Team are appealing for the family who went to help the victim to contact them.
The incident occurred at around 1.15pm on Sunday, February 9, when the woman, who was wearing a red duffel coat, was walking along Cockshot Hill between Canon and The Angel pub.
Investigating officer PC Tim Dobiz, said: "Assaults of this nature are extremely upsetting for the victim and any witnesses, but the fact the victim in this case is heavily pregnant makes it even more disturbing.”
PC Dobiz said after the assault, the victim was able to tell officers a family had intervened and even given her a lift home.
He said: “But we have not yet been able to identify them and I would urge them to make contact with us.
"All information passed to us will be treated in the strictest of confidence.”
He added: "The family deserve praise for their actions, but I truly believe they will also be able to provide vital information to assist our investigation.”
Officers would also like to trace three runners who stopped and spoke to the offender.
The spokeswoman said: “Neither the woman nor her unborn child suffered any physical injuries as a result of the assault.
“A man in his 20s from Crawley was arrested on suspicion of assault, and has been released on conditional police bail until Monday, March 10, while the investigation continues.”
Anyone with information is urged to contact Surrey Police on 101, quoting reference 45140010250. Alternatively, people can call the independent charity Crimestoppers anonymously on 0800 555 111.