As Christchurch readies itself for what will be a lengthy clean up after Saturday morning's earthquake, Kiwis are being warned that cyber criminals are readying for a spam assault cashing in on the disaster.

Security specialist Symantec says spammers are quick to prey on the emotions of people following a disaster - citing a massive outbreak of spam following the Haiti quake earlier this year.

Bogus emails and phony websites are often used in phishing expeditions that are aimed at thieving what should be charitable donations.

To ensure that donations reach those who need it, Symantec - which makes the popular Norton range of security products - warns internet users to stay vigilant, and to avoid following links to 'charity' sites in emails or in instant messages.

Symantec experts advise to type web addresses directly into your browser in order to avoid spoofed sites designed to siphon donations. Do not simply copy an address from an email message, this could still lead to a site controlled by cybercrooks.

Those wanting to make donations to help the clean-up in Christchurch should avoid filling out forms in messages that ask for personal information or passwords.

Reputable charities are unlikely to ask for these sorts of details. If internet users have any doubt about a site, Symantec recommends contacting the organisation through trusted mechanisms like a verified telephone number or a known internet address.