Police have issued an appeal for information regarding the alleged incident, which took place between approximately 20:55 and 21:10 on Friday 20 September.
According to the police appeal, a man and woman in their 30s walked through town arguing.
It is alleged that the man “repeatedly assaulted” the woman during their journey.
Police said that the pair walked from the area near Chambers in Mulcaster Street to Beresford Street via Hill Street, Halkett Place, Queen Street and Halkett Street – where members of the public intervened.
The man was wearing a grey t-shirt and dark workman’s trousers.
The woman was in a black top and trousers.
CAN YOU HELP?
Police would like to speak to anyone who saw the pair and can provide any information about exactly what happened.
This includes drivers who were in the area at the time and may have dash-cam footage.
Anyone with information is asked to contact police on 612612, or the independent charity Crimestoppers anonymously on 0800 555 111 or via their anonymous online form at Crimestoppers-uk.org.