Four more people have been charged over their alleged role in a compulsory third party (CTP) insurance fraud syndicate operating across Sydney.

With the support of the State Insurance Regulatory Authority, NSW Police formed the Strike Force Ravens taskforce to crack down on fraud after CTP premiums spiralled.

So far investigators have arrested 27 people and laid more than 170 charges in relation to a combined fraud of more than $11 million.

On Tuesday, detectives executed search warrants at properties in Pyrmont and Bass Hill, and a Bankstown medical practice.

Investigators seized items including electronic devices and “documentation relevant to the investigation”.

On the same day, a 45-year-old Bass Hill man was arrested and charged. He remains before the courts.

On Wednesday, detectives also arrested and charged a 36-year-old man at a home in Merrylands, a 40-year-old woman at a home in Cherrybrook, and a 43-year-old woman at Castle Hill Police Station.

Police allege the man and women fraudulently submitted CTP insurance claims.

The NSW Government says the fraud crackdown, along with reforms to the greenslips system, has sent CTP prices plummeting, with the average state-wide premium at an eight-year low of $495.

Finance, Services and Property Minister Victor Dominello says the new scheme, which came into effect in December 2017, has resulted in cheaper premiums, faster benefits paid to those injured, and a partial refund worth up to $120 for most motorists.

“In 2016 an independent report showed that without reform, average CTP premiums may have exceeded $785 by 2018,” he said.

“As a result of the scheme overhaul, there has been nearly a $300 turnaround on what motorists would have been paying now.

“These savings have been made possible by reducing insurer profits, cracking down on fraudulent and exaggerated claims and slashing legal costs.”