TORONTO - The coalition running pre-election ads targeting the Conservatives is "an independent organization'' despite alleged ties to the Liberals and the Opposition's request for a formal Elections Ontario investigation, Premier Dalton McGuinty said Friday.

The Conservatives say the governing Liberals are violating Ontario's Election Act by having a third party buy television commercials to promote their re-election bid.

The party has asked Elections Ontario to investigate the Working Families Coalition's close ties to McGuinty's former chief of staff, who now runs the polling firm Pollara and is one of the coalition's main organizers.

But McGuinty said that firm also has many other clients besides the coalition, which he maintained is totally independent from the Liberals.

"They're an independent organization and they're going to do whatever they want to do,'' McGuinty said repeatedly when asked Friday about the Conservative claims following a speech to Liberal candidates in Toronto.

The coalition, made up of various unions, was responsible for the "Not this time, Ernie'' campaign that helped defeat the Conservatives under Ernie Eves in 2003.

The group is now running television ads telling voters that the governing Liberals have brought peace and stability to Ontario schools, unlike the previous Conservative government. The ads are also critical of the Conservative plan to extend public funding to private religious schools who become part of the public system.

Conservative party president Blair McCreadie said the party welcomes the participation of third parties in the coming election campaign, but said the Working Families Coalition is just a front for the Liberals.

The two key firms devising the coalition's strategy are Liberal-friendly and received some $3.8 million in government contracts from the McGuinty government, he said.

"At the end of the day, there is compelling evidence that there is a relationship here,'' McCreadie said. "Obviously the premier is going to say they're an independent organization. That's not unexpected.''

The party wants an Elections Ontario investigation completed before voters go to the polls Oct. 10. Since parties are only allowed to spend up to about $6 million on election advertising, McCreadie said the Liberals should have to foot the bill for the coalition's $4-million ad campaign if they breached the rules.

But Finance Minister Greg Sorbara said it's natural that a variety of coalitions will wade into the election debate, which he said makes for a "healthier campaign.''

"I have seen the work of the Working Families Coalition. ... I'm not surprised they're active in this campaign as well,'' said Sorbara, adding the group is not connected to the Liberals.

"They have a right to express an opinion during a campaign.''

NDP Leader Howard Hampton said the Liberal defence has little credibility given the recent controversy over end-of-year grants to multicultural organizations which the opposition alleged had Liberal ties as well.

"It's pretty clear that the principle organizers (of the coalition) have very close connections to the Liberal party,'' he said. "Hopefully that will all be disclosed.''