The Warehouse will consider asking authorities to investigate tactics by a rival as competition for the back-to-school stationery dollar heats up.

In full-page newspaper advertisements, it has called for parents to tell it about instances when schools insist they buy certain stationery packs and refuse to give out stationery lists.

Warehouse Stationery and Warehouse chief executive Mark Powell said so far the response had been strong, with many parents saying schools were being excessively prescriptive. Most instances involved competitor Office Max, he said. "Parents should be able to get the [stationery] list, without having to chase it, and some parents had to be very forceful to get anything."

But the move has been dismissed by Office Max as a campaign for market share.

Advertisement, run by Office Max, lets parents buy all required stationery for their children by entering a school name and class.

Supplies are paid for online and delivered, and the school receives a small cut of the sale.

In most cases, the required stationery is itemised and can be removed, letting parents shop around. But for some schools, contents of students' stationery packs are hidden on the website, which reveals only the price.

A previous Herald survey found prices from Office Max were generally competitive. But a few items, such as pencils, coloured pencils and highlighters, could be bought at a big discount elsewhere.

Office Max general manager (education) Suzanne Flannagan said fewer than 30 schools had chosen to list "closed" packs on the Myschool website.

She said schools selected a supplier to provide commonality and ensure all children started the year with the correct supplies.