New Zealand's top cop says he can't speak directly on his Deputy Commissioner's resignation - but has acknowledged it's raised questions

Jevon McSkimming's under criminal investigation - but the nature of the allegations can't be reported.

He stepped down earlier this week, after being suspended on full-pay since December - and it's understood porn was also allegedly found on his work computer.

Police Commissioner Richard Chambers says he can't comment on the circumstances without compromising the investigation.

He says he has high expectations for staff - and will act to address anything that puts the reputation of police at risk.