Children that spend too much time engaging with digital screens risk being exposed to harmful advertising, an expert warns.

Wiremu Manaia, a senior lecturer in technology at Manukau Institute of Technology told TVNZ1's Breakfast his biggest concern is "screen time technology addiction" and the impact online advertising has on children.

Examples of harmful advertising are messages about fast food, gambling and tobacco and alcohol.

"They’re on screens before they go to school, they’re on screens at school and they’re on screens when they get home from school ... they’re on screens from 10-12 hours a day."

"The advertising is a ploy ... it's attracting them into areas that we probably shouldn’t be exposing our children to."

Watch the full interview below.

One News - 'It's hitting them young' - too much screen time risks exposing children to harmful advertising, expert warns