TORONTO - Ontario retailers should consider listing the new eco fees on price tags and shelf labels to improve a program that's caught many frustrated consumers by surprise, Environment Minister John Gerretsen said Wednesday.

"That may be an excellent idea," Gerretsen said in an interview with The Canadian Press. "That's certainly worth looking at."

It's all about making the new fees more transparent, he said, which have been mired in controversy since retailers began to apply them to a wider array of consumer products July 1.

The money goes to a recycling program that diverts potentially hazardous items, such as fire extinguishers, household cleaners and paint, from Ontario's landfills.

But there was no public warning that the eco fee, which was first introduced in 2008, would be slapped on thousands of new items.

Stewardship Ontario, an industry-led organization that oversees the program, collects certain fees from retailers and manufacturers. They, in turn, determine the fees that they pass on to consumers.

The fee can be embedded in the product or the sticker price, which means in some cases, shoppers won't know when or how much they're being charged.

Some are scratching their heads about why certain items are subject to the levy, such as fish bowls, grass seed, kids bath toys and environmentally friendly products that use natural ingredients.

At least one large retailer ended up overcharging customers amid all the public confusion, prompting a stern rebuke from Gerretsen.

"People want to do the right thing, but they shouldn't be gouged by perhaps some unscrupulous retailers that are taking advantage of the situation," he said.

"And if Stewardship Ontario cannot resolve that, then obviously we within the ministry and the government would have to take some pretty decisive actions as to what the future of the eco fees is going to be."

Gerretsen warned Stewardship Ontario in a letter Tuesday that he has "serious concerns" about the availability of information about the program and ordered them to stop retailers from overcharging customers.

"If the program is not accountable, transparent and subject to audit so that consumers are not paying more than they should, then we may have to take a look at perhaps getting rid of eco-fees altogether," he said Wednesday.

Stewardship Ontario may also see some changes to how it operates, he said.

The government is planning to make changes to the current legislation that allow it to exert more control over the agency, he said.

"It's my understanding that a new organization would be set up," Gerretsen said. "As to how much it's going to look like the old organization -- or who's going to be involved -- I'd rather not get involved in that."

The fee flap has provided powerful ammunition for the opposition parties, even prompting the Progressive Conservatives to make their first election promise to kill the "eco tax" if they form the next government in 2011.

Both the Tories and NDP say the government must find out where the money collected through their controversial eco fee is going, or leave it to a third party like the ombudsman to find out.

"Taxpayers, businesses, we all have a responsibility to now call on the government to give us an account of what this agency has done since it began collecting these fees -- multi-millions of dollars," said Progressive Conservative Frank Klees.

"Where have those millions of dollars in fees gone? What has this agency done to divert hazardous waste? Where is the money, apart from growing another bureaucracy, apart from confusing the general public and businesses as well?"

The New Democrats have asked Ombudsman Andrea Marin to investigate the fees and how they were rolled out, while Conservative critic Lisa MacLeod is calling on the province's auditor general to conduct a forensic audit of Stewardship Ontario.

The organization says it's already overseen by Waste Diversion Ontario, a regulatory body, and audited each year by an independent third body. Its financial statements are published in an annual report that is available on its website.

The New Democrats are still planning to haul executives from Stewardship Ontario and Waste Diversion Ontario before a legislative committee.

"The minister's letter is an exercise in covering your butt," said NDP Leader Andrea Horwath. "It's just a big mess and a huge fiasco."

Canadian Tire, which overcharged some customers, blamed the problem on a programming error and planned to fix it by Wednesday.

It has apologized to customers and promised to reimburse the difference between the incorrect fee and the correct one. Any money not reimbursed to customers will be remittted to Stewardship Ontario for the recycling program, it said.