Woman's body is removed from derelict building's premises.

Police are investigating a mysterious murder after the body of an unknown woman was found buried in a shallow grave.

A passerby made the gruesome discovery in a derelict building along Voortrekker Road, Maitland, on Tuesday.

Police say the body was already “badly decomposed” when it was found.

It’s believed the body was wrapped in a blanket before it was stuffed in a ditch.

Employees at a nearby factory told the Daily Voice they were not aware of any murder.

Police spokesperson Captain Frederick van Wyk says an investigation is underway.

“The badly decomposed body of a female was discovered by a passerby in a shallow grave inside a dilapidated building along Voortrekker Road, Maitland,” he says.

“(The passerby) alerted Maitland police who responded.

“The age of the person is unknown at this stage and investigations surrounding her death are underway.

“A murder case was registered for investigation,” Van Wyk says.