AN autistic boy was kidnapped, tortured, bashed and sexually assaulted after he was allegedly set upon by two young girls during a depraved attack in suburban Townsville.

The 12-year-old boy was riding home after fishing in a creek, when he was pulled from his bike and dragged into a house that was under construction on Sunday, The Townsville Bulletin reports.

He was then subjected to a prolonged and humiliating assault allegedly at the hands of two girls, aged just 13 and 14.

The boy was bashed, threatened with a knife and stripped naked before being sexually assaulted during the terrifying ordeal.

The young victim managed to escape and ran to a house next door, screaming for help, where the home owners took him inside and phoned his mother.

The boy's mother, who cannot be named as it would identify her son, said the boy wasn't able to communicate how long he had been held captive, but believes it may have been around an hour.

Two girls have been charged over the attack.

Read more at The Townsville Bulletin website.