It is understood the incident took place at a unit in Wollongong about 1.30am on Sunday.
At the unit, De Belin and another Dragons player allegedly engaged in a sexual act with a 19-year-old woman.
The 27-year-old Dragons forward voluntarily attended Wollongong Police Station today and was then charged with aggravated sexual assault in company.
The Dragons informed the NRL’s integrity unit of the alleged incident as soon as they became aware of it.
The club released the following statement on their website earlier.
The club is taking the matter very seriously and have been working with Jack and all relevant authorities, including the police and the NRL Integrity Unit, since this time.
Jack has been provided with welfare support to enable him the time and opportunity to deal with the matter.
As this is a police matter to be considered by the court, the club is not in a position to make any further comment at this time.