Fresh warnings about scammers claiming to have hacked webcams, as the number of reports jumps over the long weekend

The scam is also known as "sextortion", and involves the crook sending an email claiming they have a copy of someone's pornography viewing history ... and they've been recorded through their webcam.

The Government cyber-security unit - Cert NZ - says over the past three days it had as many reports of the scam, as in the whole month before.

CERT NZ Operations Manager Declan Ingram says the scams can sound legitimate - especially when the scammers show the victim one of their own passwords, which has really come from an online data-dump.

But he says they've seen nothing to prove the blackmailers have what they claim.