Scammers impersonating detectives are targeting people who own cryptocurrency and stealing millions of dollars, police say.

Police have received multiple reports in recent weeks about the scam which they said appeared to be on the rise.

Detective Inspector Stuart Mills said the scammers were posing as detectives, often claiming the victim's details, information, or identity documents had been found on a person who had been arrested.

"The fake detective directs their questions towards establishing if and how the victim holds cryptocurrency, before arranging for a fake representative from the cryptocurrency company to contact the victim.

"The fake representative then convinces the victim to hand over their passwords or seed phrases, often through a fake webpage resembling a legitimate cryptocurrency application."

Police urged people to protect their cryptocurrency information, and not to give it out to anyone they weren't familiar with.

While legitimate police officers would contact people as part of their duties, Mills said, they would never ask for sensitive financial details.

Police warned scammers could spoof legitimate police phone numbers and email addresses, so this was not a reliable way to check who was contacting you.

If uncertain, people should ask for the officer's details, hang up, call 105 and request that officer call back.