Seven people have been arrested over an alleged billion-dollar scam where former young offenders, inmates and school students, under the guidance of a crime syndicate, filed false sex abuse claims with the NSW government.

According to the Sydney Morning Herald, a third of the population at one NSW prison has submitted claims, and multiple law firms are now under investigation for their roles in thousands of “strikingly similar” complaints.

On Thursday NSW Police alleged they had caught “claims farmers” behind $1.3 billion worth of claims, many of which were fake.

Four men and three women were rounded up across Sydney and Gold Coast, among them, 55-year-old Fotis Antonios from Girraween in Sydney’s west.

Police allege he was a chief of the syndicate.

“He’s made hundreds of thousands of dollars, if not a million dollars; he is the [alleged] syndicate head,” Detective Superintendent Gordon Arbinja told media on Thursday.

It’s alleged that Antonios and others were instructing complainants to pursue their claims against the government departments under the National Redress Scheme, the police Sexual Assault Reporting Option and through civil litigation.

They would submit the claims and pocket at least $2200 for each and Antonios allegedly had 100 claims pending alone.

The law firms used to enact the scams and the fake victims would split the remainder of the payouts said Arbinja.

Nearly 4000 claims were identified with most being similar.

It’s said the alleged fraudsters stood to make $3.75 million if the claims were paid out.

Police said they hoped the arrests and conversations with government now under way would “stop the bleeding”.

“NSW Police support legitimate victims; they should be compensated. The problem is the system is porous and needs to be strengthened,” Arbinja said.

“Unfortunately, in this instance it’s been exploited by an organised criminal network.”

Antonios faces Parramatta Local Court on 21 charges, including fraud, misleading documents and inciting others to do the same.

Others arrested include a woman in Granville, 53, a man and woman in Pendle Hill, 32 and 35, a man in Gladesville, 42, and a woman in Horsley, 52.

All are expected to face court next month.

Lifeline 13 11 14

National Sexual Assault Counselling Service 1800 RESPECT (1800 737 732)

National Sexual Abuse and Redress Support Service 1800 211 028