TORONTO - With public funding of religious schools shaping up to be a "defining issue" in Ontario's upcoming election campaign, Premier Dalton McGuinty warned Wednesday that an Opposition plan to fund non-Catholic religious schools would separate rather than unite people of diverse backgrounds.

Conservative Leader John Tory has said if he's elected premier he will extend public funding to Jewish, Muslim and Christian schools in Ontario that agree to follow the provincial curriculum, calling it a matter of fairness.

At the same time, the Ontario Green party is campaigning on a proposal to end public funding of Roman Catholic schools, a practice that has been condemned by the United Nations as discriminating against other religions.

Entering his last scheduled cabinet meeting Wednesday before the Oct. 10 election, McGuinty dismissed both the Conservative and Green proposals, and said it was important to keep building on the existing public education system.

"I don't think that Ontarians believe that improvement or progress is defined as inviting children of different faiths to leave the publicly funded system and go to their own schools," McGuinty said, adding it could well become a defining issue for the campaign.

"I think that's regressive. I think that takes us backwards. I think our responsibility is to continue to improve the publicly funded system of education."

While dismissing Tory's proposal, McGuinty had only a very brief defence of the government's policy of fully funding Roman Catholic schools but not those of any other religions.

"That's the system that we have inherited," McGuinty said.

Ontario Green party Leader Frank de Jong said McGuinty's defence was "not a very progressive position," especially since the premier says kids from all religions except Catholicism should be studying together to help create a more united society.

"It's not fair to fund only one religion, and so the status quo is untenable and it has to change," de Jong said.

"Either we go to funding all religions - which of course is a can of worms - or we go like Quebec, Manitoba and Newfoundland and switch to just funding one school system for each language."

Quebec gives all faith-based schools about 60 per cent of the funding public schools receive. Alberta allows faith-based schools to be funded as part of public boards. It also provides 60 per cent of public-school funding to private schools, including faith-based ones.

Nova Scotia does not fund religious schools at all.

Conservative Leader John Tory said his plan doesn't encourage segregation but rather would bring students into the public system who are alienated now because they don't attend either public or Catholic schools.

"There are 53,000 students across this province who are in schools where we don't know what they're being taught or by whom," Tory said in reference to students currently attending private religious schools. "I want to bring those students in and make our public education system more inclusive."

McGuinty is just "playing politics" with an important issue and policy proposal that recognizes the face of Ontario is changing, he added.

But McGuinty said an important part of Ontario's success as a multicultural society is that the existing public education system lets kids of all faiths learn together.

"An important part of our foundation for social cohesion is a publicly funded education system where we invite children of all backgrounds and faiths, economic circumstances, to come together to learn from each other and to grow together," he said.

"It's one of those issues where I'm hoping to grab Ontarians by the earlobes and say it's not just another election, it's about the kind of Ontario you want."

NDP critic Peter Tabuns said the New Democrats also support maintaining the status quo in public education, but with one key proviso.

"We need to put money back into the system to deal with the fundamental problems that teachers and students are dealing with," Tabuns said.