A comment by Toronto Mayor Rob Ford suggesting advertising be allowed inside school buildings is causing some controversy.

Speaking on a local radio station last week, Ford suggested companies could pay to advertise on gym floors and walls inside schools.

In the Thursday interview on the Fan 590, Ford said it's ridiculous that school gymnasiums sit empty when they could be generating revenue.

Parent Leslie Middaugh said schools aren’t the right place for advertising.

"Even if you carefully choose who you allow to advertise in schools you are endorsing that company, you are endorsing that product," she told CBC News.

Middaugh said she could never support advertising in school hallways or gyms.

A 'slippery slope,' trustee says

Trustee Chris Glover agreed, and said Toronto public schools are no place for ads.

"Advertising is not a donation, it’s a business deal," said Glover.

"And what the corporations want is access to our students in exchange for money. The danger is that it’s a real slippery slope. Once you become dependent on private advertising revenue then you have no way of backing out."

School Board trustee Howard Kaplan said Toronto school gyms are used regularly by community groups outside of school hours for minimal fees.