Ten officers are working on the investigation and a scene examination has now been completed at the motel.
Police are not prepared to release any further details at this stage, Mr Forlong said.
South Canterbury Rugby Union chairman Brent Isbister told the Chronicle he had learned of the allegations only today.
"This is very distressing for everybody involved, and from a South Canterbury rugby perspective it is very disappointing,'' Mr Isbister said.
"Quite obviously our union will be working with police to help with their investigations.''
He said others on the province's rugby board had been made aware of the allegations but there was no intention at this stage to call a special meeting.
"We'll let the police work through their investigation and that's all I'm prepared to say at this stage.''
Wanganui Rugby Union chief executive Dale Cobb told the Chronicle he had spoken to New Zealand Rugby as well as his counterpart at the South Canterbury Rugby Union in Timaru.
"Given the sensitive nature of these allegations and the seriousness of them, it's only right that we're working off the same page with any comment we make,'' Mr Cobb said.
"We're certainly encouraging the police investigation to run its course and for that reason there's nothing more I can add at this stage.''
He said he was expecting the national body to make a statement about the alleged incident.
