Published Thursday, 04 September 2014
The alleged attack happened one week ago in Portrush. (© UTV)
It happened in the Dunluce Road area of the Co Antrim town sometime between 1.30am and 2am on Thursday, 28 August.
Detective Inspector Adrian Brown said: "The two males made off when another female, unknown to the injured party, shouted at them. This female was wearing a red dress and helped her onto a bus marked "DC Bus".
"I would appeal to this female to come forward and contact me to assist with the investigation."
He added: "I would also appeal to anyone who knows anything about this incident to contact us on the non emergency number 101.
"Or if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111."
© UTV News