Police are making enquiries at an address in Park Parade, Leigh Park, over the allegations.
They are reported to have taken place between Monday and the early hours of Tuesday.
Three men from Havant, 20, 36, and 43, have been arrested on suspicion of a number of sexual offences.
Now police want to speak to anyone who was in the area of Park Parade on Monday evening.
Chief inspector Clare Jenkins, who is in charge of policing in Havant said: ‘We continue to investigate the exact circumstances of the incident, however I understand that investigations of this nature can cause concern in the community. My team is always available for advice and support and we will be carrying out regular patrols in the area.
‘We are keen to speak to anyone who may have been in the area of Park Parade on Monday evening and has not yet spoken to us, you could hold vital information which could help us.’
Anyone with information should contact DI Adam Price at Fratton Police Station on 101 quoting Operation Tent.
Alternatively, call Crimestoppers anonymously on 0800 555 111.