Renowned Australian artist Pro Hart's grave in Broken Hill has been defaced by vandals, leaving his family "horrified" and "devastated".

Key points: Pro Hart died in 2006 and was laid to rest beneath a $60,000 granite memorial

Pro Hart died in 2006 and was laid to rest beneath a $60,000 granite memorial Photos on social media show the gravesite has been defaced, apparently with acid

Photos on social media show the gravesite has been defaced, apparently with acid Hart's family and the Broken Hill community has expressed shock, sadness and outrage

During his life, Hart was recognised as a pioneer of Australian outback art, and received numerous awards for his paintings and sculptures.

He died in 2006 at the age of 77 and was laid to rest beneath a $60,000 granite memorial etched with a gold dragonfly at the Broken Hill Cemetery.

However, his family has posted photos on social media showing the once-gleaming grave smeared with an unknown substance, believed to be acid.

Hart was born in Broken Hill and remained strongly associated with the silver city. ( David Hart Galleries )

"I can't understand why anyone would want to deface it. Pro loved this town and to have this happen just doesn't make any sense," Hart's son John said.

"It's just disrespectful, but it's disrespectful for anyone's grave to be attacked in this way. Any family would be horrified."

John Hart said the wider Broken Hill community was "equally horrified" by what had occurred, and described the vandals responsible as "idiots".

"Occasionally you get a tourist stand on it to get a photo or something but otherwise, no, it's just a memorial," he said.

"What's even more disturbing is none of the other graves have been targeted, so it looks like this one was it — they had every intention of putting a mark on it. Poor Mum's devastated."

David Hart — another of Pro's sons and a fellow artist, based in Queensland — also expressed distress.

"This is absolutely heartbreaking for our family and I don't understand why someone would do this," he posted on social media.

The grave with its gold dragonfly headstone before it was defaced. ( Facebook: John Hart )

"My mum called me this afternoon sobbing to give me the news that vandals have thrown acid all over my father's grave.

"It has etched into the $60,000 granite memorial and has destroyed the surface as well as the side skirts and steps."

Detective Inspector Michael Fuller said police had attended the scene, and confirmed other graves had not been vandalised.

"We had our crime scene [detectives] here this morning to take samples and photographs," he said.

"There's no indication of any paint substance or any other physical damage around here, so it was a reassurance to people that have friends, family and relatives that are buried here.

"No suspects have been identified at this point."

Broken Hill Mayor 'completely shocked' and 'outraged'

Born Kevin Hart in Broken Hill in 1928, Pro secured his moniker after mining mates nicknamed him "Professor" because of his passion for inventing things

A miner's helmet was placed on Pro Hart's coffin at his funeral in 2006. ( ABC TV )

The self-taught, internationally acclaimed artist was a much-loved and colourful character who could also be controversial. He once described his critics as an "art mafia".

John Hart said whatever substance the vandals had used had "burnt into the granite", and repairing the grave would be a "nightmare".

"We'll do what we can to rectify it, as best we can and … we'll think about changing the memorial to something a little bit more vandal-proof," he said.

"It just looks pretty shabby now. I just can't even think how much it's going to cost to repair it. It was about $60,000 to build it. If we can't buff what's been etched in out, it'll have to be dismantled, sent to Queensland and the whole thing just redone again and that could be $20,000 to $30,000 of repairs.

"There's no guarantee that it won't get hit again at another time."

Broken Hill Mayor Darriea Turley has expressed outrage on behalf of the local community. ( ABC News )

Broken Hill Mayor Darriea Turley expressed her sympathies to Hart's widow and children, and said she shared the "outrage of the Hart family".

"I was completely shocked," she said.

"It is not a random crime, this is actually not random. Someone's planned this specifically.

"To actually target one grave and to come out to Pro's grave — the most iconic man in Broken Hill — who lays here with many others … this is outrageous."

Ms Turley said it was not uncommon for tourists and locals to visit the site to pay their respects to Pro Hart.

Local police have asked anyone with information to contact them or call Crime Stoppers on 1800 333 000.