Police are investigating a scam targeting admin staff at Christchurch schools.

Senior Sergeant Nicola Reeves says it has affected a number of schools and universities in the Canterbury area.

Reeves says people are emailed by a person pretending to be the principal, who asks them to buy gift cards for the App Store or iTunes and send them the numbers.

"Scams of this nature are sophisticated and create a sense of urgency. If people get requests to buy gift cards, they should get in touch with the person who supposedly sent the email and check."