The Irish National Teachers' Organisation has said teachers should not support advertising schemes by commercial companies that target children or their families through schools.
The primary school union was commenting as Independent Newspapers Ireland and Bank of Ireland launched a competition for schools that requires children to collect tokens from newspapers.
Independent Newspapers says the scheme - called Building for the Future - is a fun, education-based project that will enrich primary schools and their communities.
However, the INTO has called it a new low in targeting children for commercial gain.
The union says Bank of Ireland has been bailed out by the taxpayer and should not now be using that money to promote its products to schoolchildren.
INTO President Máire Ní Chuinneagáin said the union would make a public protest against the promotion if it is not scrapped by the companies involved.
The competition invites primary schools to enter projects on a local business in their area. It offers prizes of up to €20,000.
The INTO says a 300-pupil primary school would have to purchase more than €10,000 worth of newspapers in order to collect enough tokens to enter the competition.