Man charged with raping girl, 15

A 29-year-old man has been accused of holding a teenage girl hostage inside a Sydney house for a month and sexually assaulting her.

The man was arrested after police saw him chasing the 15-year-old along a Blacktown street before grabbing the teen and trying to drag her away around 1.30am on Thursday.

The girl told police the man had been holding her against her will for four weeks inside a Balmoral Street house, where he allegedly raped her.

The girl was reported missing from a residential out-of-home care facility in October.

She was hospitalised for medical assessment and has since been released.

Child abuse squad detectives have raided the Balmoral Street property and seized a number of items.

The man has been refused bail to face Blacktown Local Court on Friday charged with aggravated sexual assault and common assault.

The Department of Family and Community Services has been notified.

The Department of Immigration and Border Protection have also been told of the man's arrest.