A Facebook site entitled "Keep Dennis Ferguson out of Ballarat" rocketed from 150 members on Monday to more than 1400 yesterday afternoon, with many members posting threats of violence towards the convicted child rapist on the site wall.

But the creator of the group, a young Ballarat mother who declined to be named, yesterday admitted the claim that Ferguson had moved to Wendouree was based on nothing more than several unconfirmed sightings at a local shopping centre.

She said she formed the group simply as an awareness campaign for other parents and was unprepared for its rapid escalation.

"A lot of people were concerned they had sighted him, so I set it up to raise awareness he is either living in or visiting the Wendouree area," she said.

But Ballarat police Criminal Investigations Unit Detective Senior Constable Kevin Carson said Ferguson, 61, who is on the sexual offenders register for life, had not moved to Ballarat.

"Ballarat CIU has not been informed of Dennis Ferguson living in Ballarat," he said.

Ferguson's location has been unknown since he left the Sydney suburb of Ryde last year, after his presence ignited a vitriolic response from neighbours.

He appeared in a Sydney court last week where he was granted an apprehended violence order against one of his former Ryde neighbours.

New South Wales police quashed rumours last week that Ferguson had moved to a refuge near Woy Woy.

Similar claims were made on Facebook in December when Ferguson was reported to be living at Doonside. This allegation also proved false.

Ballarat police Inspector Gerry Rudkins yesterday warned Ballarat residents against taking the law into their own hands in what could prove to be a case of mistaken identity.

"I would urge people to be careful, police can never condone people taking the law into their own hands because they just end up in trouble themselves," he said.