Scammers have already collected thousands of dollars from a new email extortion scam.

Waitemata Police have sent out a warning about emails being sent telling victims their computer's been hacked.

The email tells people a video's been taken through their webcam showing the user looking at pornographic websites.

Scammers then threaten to send the video onto friends and family unless $1900 in bitcoins is paid.

Police say these types of emails should be deleted - but some victims have become so concerned that they've paid money to the scammers.

The scam also claims to know victims' passwords, and in some cases lists previous passwords obtained through online data breaches.