A police officer has quit amid allegations he stole sunglasses from Christchurch's red-zone.

A police spokesman confirmed the officer resigned late last year after being investigated for theft in the aftermath of the February 22, 2011 earthquake in Christchurch.

It was alleged three sets of sunglasses were taken from a cordoned-off suburban shop by the North Island police constable.

Assistant commissioner south Dave Cliff said the matter was investigated as soon as it was brought to police notice.

An inquiry was conducted by senior police investigators and the constable was suspended once evidence of his involvement emerged. But, he did not admit the theft of the sunglasses.

"We are very clear that any allegations against police must be investigated thoroughly and promptly."

Cliff said there was not enough legal evidence to prove a charge of theft.

"Fingerprint evidence was not able to be put to the court. Officers' fingerprints are recorded for elimination purposes, but it is not lawful for these to be used for any other purpose. As a result the decision was made, reluctantly, that charges could not be brought against the constable."

Cliff said police then started a disciplinary process, which culminated in a disciplinary hearing. However, the constable resigned before the process was finished.

"The officer was the subject of a full investigation and his police career is now over."

He was satisfied the police had investigated the incident "promptly and fully".

Cliff condemned the actions of the police officer for tainting the efforts of thousands of other officer from New Zealand and overseas who helped in Christchurch.

He called it a "tragedy".

"We demand the highest ethical standards from all police officers and police employees."