Officers have released images of the two men they want to speak to as Sussex Police continue to appeal for more information.
Det Insp Booth added: “We are supporting the victim as our enquiries continue.
“Steine Lane is an area often walked both in the day and at night due to it being a popular cut-through route connecting East Street to Old Steine, and we know there were a number of people in the area around the time of the attack.
“I would urge anyone who witnessed any suspicious activity in the area around that time, or anyone who recognises the two men in these images, to please come forward.
“Your information could be key as we work to identify those responsible.
“There is no place for sexual violence in Sussex, and we take any reports of this nature extremely seriously.”