Police are investigating after a woman was sexually assaulted the backyard of a Calala home on the weekend.

About 10.30pm on Saturday 23 January 2016, a 22-year-old woman was at a home in Harrier Parade, when she went into the backyard.

As she was returning to the house, she was approached by an unknown man who sexually assaulted her, before running away.

The woman sought treatment at Tamworth Hospital.

The matter was reported to officers from Oxley Local Area Command who commenced an investigation into the incident.

Police also received a report that earlier in the night (about 9.40pm) an unknown man was seen in the backyard of a nearby home in Boronia Drive.

He was only described as wearing a hooded jumper.

Local detectives are now being assisted by officers from State Crime Command’s Sex Crimes Squad as investigations continue.

They would like to speak to anyone who saw a man acting suspiciously in the Calala area at the time, or anyone who has any other information that may be able to assist, to come forward.