TORONTO -- Ontario's new environmental commissioner says she's not trying to target farmers by asking questions about the provincial tax exemption they get on diesel fuel.

Dianne Saxe says the recent climate change talks in Paris focused on ending fossil fuel subsidies globally, and she raised the farmers' exemption from Ontario's 14.5-cent-a-litre tax on diesel when asked for an example.

"Perhaps we could, for the same money, treat farmers more fairly, get cleaner air and do less climate damage," Saxe said in an interview. "It sounded as if I was against money for farmers, which couldn't be farther from the truth."

Saxe insisted she's not saying the diesel tax exemption is a bad thing, or trying to dictate what the policy should be, but said it's something that should be looked at.

"The whole world is looking at fossil fuel subsidies," she said. "I'm just asking: why do we have this? Could we do it better? And I think it's possible we could."

The tax exempt diesel is dyed red in Ontario and is referred to as "coloured" fuel, and can be used for unlicensed construction, forestry, mining and farm equipment.

About $190 million a year is not collected in diesel tax in Ontario, and Saxe said she's not convinced most of that fuel is being used by farmers.

"Most of it, as far as I can tell, goes to other industries," she said. "I'm still trying to get those numbers from the ministry of finance."

The Ontario Federation of Agriculture doesn't like to hear the tax exemption called a subsidy -- Saxe is careful to point out she's using the legal definition from the World Trade Organization -- and said the environment commissioner's initial remarks upset farmers who thought she was setting government policy.

OFA president Don McCabe was pleased to hear Saxe said she was merely raising questions about the issue, and agreed it was good to have a debate about the role of the farm sector in combating climate change.

"I applaud the environmental commissioner for trying to find opportunities to work with farmers," he said.

The Progressive Conservatives say it would be "irresponsible" for the government to end the exemption for farmers, while the New Democrats said there would have to be a long public consultation on any proposed change to the diesel fuel tax.

"What got people's backs up was that it seemed as if this was just coming out of nowhere," said NDP agriculture critic John Vanthof, a retired farmer.

"There's an awful lot of things that farmers have been doing, and could be doing in the future, to help with climate change, and just talking about charging more for diesel fuel is not the issue."

Farmers already play an active role in environmental protection, added McCabe, capturing carbon dioxide in the form of organic matter in soil and using cover crops to help keep phosphorus from leaching into waterways.

"We've already been doing greater and greater measures of environmental significance," he said.

Environment Minister Glen Murray said farmers do have a role to play in climate change, and the government would be leery of adding to their cost of doing business by removing the diesel tax exemption.

"We have a lot of pressures on farmers right now, so I think we'd want to be very careful before we put any more complications in their lives right now," said Murray.