Police in Sydney have launched an investigation after a 12-year-old girl alleged that she was sexually assaulted by at least five teenage boys in a bushland near a park.

The reported assault took place on 9 September near Progress Park in Auburn while an Eid festival was underway at the park. The girl was headed to the park to meet a friend.

Hundreds of Muslim families were present at the festival when the girl emerged from the nearby bushland and sought help from a family, who reported the matter to police. Police took the girl to a hospital for a sexual assault examination.

The case is being investigated by Child Abuse Response Team and the Sex Crimes Squad, a police spokeswoman confirmed to The Telegraph Australia.

Police said they have potential suspects under investigation and believe some of the suspects are related to well-known crime families in southwest Sydney.

Police suspects the accused boys are in their early teens to mid-teens.

Police have urged residents who might have information on the alleged crime that could assist the ongoing investigation to call them at 1800 333 000.