Growing opposition to free school equipment promotions has prompted Ireland's Department of Education to review policy.

Primary school principals have threatened to boycott the schemes, which are run by Tesco and SuperValu and offer sports equipment and computers in return for vouchers.

The principals claim an item such as a SuperValu football requires schools to collect vouchers from shopping worth almost €4,000.

They also claim an Apple Mac computer requires parents to spend €261,000 at Tesco. "We believe these schemes are using children as marketing tools," said Sean Cottrell, director of the Irish Primary Principals' Network. "It is unacceptable for companies to require people to spend large amounts before they will make a contribution."

A government spokeswoman said the department would consult with parent bodies and teacher unions before deciding what action, if any, should be taken.

"There should be no undue pressure exerted on parents or children by commercial interests,"she added.

SuperValu, part of the Musgrave group, said: "The equipment costs the shopper nothing - it is provided as an added-value item."

Tesco said its scheme involved "no cost to the schools".