Two men charged after two companies were defrauded of more than $5.5 million.

It comes as police issue warnings to always use a digital currency exchange approved by AUSTRAC when buying or selling cryptocurrency.

NSW Police said on June 16 detectives stopped a car where they arrested the driver and sole occupant - a 39-year-old man.

A short time later, investigators executed three search warrants at a home and warehouse in Cromer, where they seized six luxury and classic cars, as well as 11 motorcycles, seven luxury watches, nun chucks and cryptocurrency wallets.

The man was taken to Manly police station where he was charged with three counts each of dishonestly obtaining financial advantage by deception and knowingly deal with proceeds of crime.

He was formally refused bail to appear at Downing Centre Local Court on August 24.

Following further ongoing inquiries NSW strike force detectives located and seized a red Ferrari - believed to be worth $600,000 - at a car dealership in Marrickville.

NSW Police said the total value of all the vehicles seized is estimated to be about $2.7 million.

On June 21 strike force detectives also arrested a 67-year-old man at Manly Police Station.

The man was charged with dealing with property proceeds of crime and was granted conditional bail to appear at Manly Local Court on September 6.

IN OTHER NEWS:

"Police will allege in court the younger man allegedly defrauded the companies using a cryptocurrency scam, whilst the older man authorised the funds and arranged the disposal of the Ferrari on behalf of the younger man to avoid police detection."

State Crime Command's financial crimes squad commander Detective Superintendent Gordon Arbinja said the investigation was a timely reminder for people to "exercise due diligence" when buying or selling cryptocurrency.

"Cryptocurrency isn't illegal, but it is imperative that it's handled responsibly to avoid being scammed," Det Supt Arbinja said.

"When buying or selling crypto, make sure you use a digital currency exchange that is approved by AUSTRAC and always scrutinise all the details," he said.