A councillor from the Hatra area told The Daily Telegraph that the 20-strong squad of Iraqi policemen who had guarded the temple from looters had fled after the area fell to tribal militants and Isis fighters a fortnight ago.
Locals say that since then, the area has been targeted by Iraqi warplanes that have bombed the jihadists less than a mile from the temple.
"The guards all ran and left their weapons behind when they heard that the tribes and Isis were coming," said Mohammed Abdallah Khozal, the councillor whose own son was killed in the fighting with the jihadists.
"Currently there is no one protecting the temple at all, and it is in control of the rebels. I am concerned about its safety, although I am also worried about government forces doing bombing."
An oasis of pre-Christian civilisation in the middle of the desert that stretches toward Syria, Hatra's columns and statues make it one of the most impressive of Iraq's archaeological sites.
Dating back to about the 3rd century BC, it is dedicated mainly to the sun god Shamash, whose statues and masks adorn its limestone and gypsum walls.
William Friedkin, the director of The Exorcist, filmed the first scene in Hatra in which a priest at an archaeology dig unearths a talisman belonging to Pazuzu, an ancient Mesopotamian demon. A child bogeyman in Mesopotamian folklore, Pazuzu is said to be alerted whenever his talismans are disturbed or touched, and in The Exorcist he goes to possess a young girl.
For most of 40 years, Hatra and its Hollywood connection have been all but forgotten. Under Saddam Hussein, the site was effectively closed to outside visitors and since his fall, Iraq has been largely too dangerous for tourists.
Its potential as a tourist site was spotted in 2003 by US troops from the 2-320 Field Artillery Regiment who guarded it after Saddam's fall, when they were billeted in a disused hotel nearby.
They stumbled on its film connection by chance, when a captain serving with the regiment watched The Exorcist on his DVD player and realised that the opening sequence, showing the sun rising over the temple's skyline, had been shot from his hotel window.
The troops then trained up local guides, hoping what they called "The Exorcist Experience" would help to attract tourists. But Iraq's growing insurgency meant the scheme never came to fruition. Since then, the only foreign visitors to the site have been a handful of archaeologists, while some of its more valuable artefacts have been removed for safekeeping in the Mosul and Baghdad museums.
Dr Lamia Al Gailani Werr, a London-based archaeologist who works with the Iraqi national museum, said she had heard from friends that so far no harm had come to either Hatra or any of the other ancient sites around Mosul, which lies on the foundations of the ancient Assyrian city of Nineveh.
But last week, Unesco issued an urgent warning that the sites were at risk. There are fears that they could suffer the same fate as the Buddha statues in the Afghan town of Bamyan, which were blown up by the Taleban.
Irina Bokova, the director-general of Unesco, said: "I call on all actors to refrain from any form of destruction of cultural heritage, including religious sites. Their intentional destruction are war crimes and a blow against the Iraqi people's identity and history."
