SYDNEY (AFP) - An Australian man was charged on Monday with 145 sex offences against at least 28 children, including rape, after allegedly using social media to groom them.

Police claim the 47-year-old from Warwick, southwest of Brisbane, Queensland, used several aliases online - including Jazz, Jazzman and David Bourne - to prey on children under the age of 16.

His alleged crimes, including making and distributing child pornography, were committed between 2002 to 2015, and involved victims in Australia.

Police claim he asked the children for indecent photos and then used them to extort and in some cases rape, film and photograph them.

Detective Senior Constable Russell Joyce told the Warwick Daily News that a complaint was made in April last year, which sparked a lengthy investigation to track down victims.

"The reactions when we have found them have been everything from embarrassment to shock and in some respects, relief," he said.

"We are still going and we believe there are more victims out there."

Joyce added: "The Internet is where the kids are these days and it is so hard for parents to keep track of what they're doing."

Queensland Police Minister Jo-Ann Miller urged parents to closely monitor their children's online activity, giving warning that sex offenders are skilled at using technology to prey on them.

"It's not good enough to say you don't understand Facebook or you can't work out how to use an iPhone," she said.

"You need to learn about what your children are using so you can guide, assist and supervise their use."

The man, who was not named, was remanded in custody until July 20.