TORONTO -- Ontario's beleaguered premier is promising to stop an "illegal strike" by thousands of public elementary teachers who plan to walk out Friday to protest their controversial new contracts.

The teachers are no longer in a legal strike position now that the cash-strapped province has imposed new two-year collective agreements, Premier Dalton McGuinty said late Wednesday.

"To withdraw your services from our schools and your students is illegal," he said in a hastily-called news conference. "If you feel your dissatisfaction has not been heard, I assure you it has."

"But let's agree to have this matter settled in court and not in our schools," McGuinty added. "Let's leave our students out of it."

The government will apply for a cease-and-desist order from the Ontario Labour Relations Board in an effort to avert a strike that would close primary schools across the province, he said.

But the outgoing premier wouldn't say whether he'd go after teachers who walk off the job in court.

"I have every reason to believe that Ontario teachers are law-abiding, that they want to do the right thing, that they will continue to deliver their services," McGuinty said.

The Elementary Teachers' Federation of Ontario insists it's not a strike, but a one-day political protest that's protected under the Charter of Rights and Freedoms.

"This has nothing to do with revenge or anger," said ETFO president Sam Hammond. "This has to do with principled positions in terms of democracy in this province and in this country."

The Liberals argue that it's an illegal strike under Bill 115, the controversial anti-strike law that gave them the power to impose the two-year collective agreements on teachers.

Teachers can protest before or after school, on the weekend, or on a statutory holiday, McGuinty said. But not during school hours.

"Teachers can have it both ways," he said. "They can participate in a political protest, and they can live up to their responsibilities under the terms of the contract that we've put in place."

Following a meeting on Wednesday, the union representing the province's public high school teachers announced it was planning its own day of protest.

The Ontario Secondary School Teachers' Federation said in a release it would schedule a day of political protest for Jan. 16, if the government has not repealed Bill 115, and rescinded the imposed contracts and restored free collective bargaining.

"It is regrettable that the provincial government has chosen to continue down this path and not respect the rights of education workers," Ken Coran, the union's president, said in a release.

Under Ontario's labour laws, engaging in illegal strike activity can carry a penalty of up to $2,000 per person and $25,000 for a trade union.

Education Minister Laurel Broten imposed collective agreements Jan. 3 on 126,000 public school teachers and education workers, which cut their benefits and froze most of their wages to battle the province's $14.4-billion deficit.

She promised to repeal the law -- which four unions are challenging in court -- by the end of the month. But Hammond said it's an empty gesture when she's already used it to trample on teachers' rights.

"I would say to anyone who says let this go, let bygones be bygones: That's not going to happen," he said.

The protest is what his 76,000 members want, Hammond said. The union can't fine any of its members if they don't participate, because it's a protest, not a strike.

There are no plans for further protests, but the union leader said he's not ruling anything out.

"Quite frankly, with this minister, there is nothing to talk about," Hammond said. "She took a very provocative and disgraceful step in terms of implementing terms and conditions on Jan. 3. And frankly, there's nothing left to talk about."

However, Hammond said he would sit down and talk with a new premier.

Progressive Conservative critic Lisa MacLeod, who has a daughter in elementary school, said she was fielding calls all day from worried parents who are scrambling to find childcare.

"The premier didn't really tell us that teachers will be in class Friday," she said. "He just hopes that."

McGuinty's shortsighted and unconstitutional legislation has brought nothing but turmoil to Ontario schools, said NDP education critic Peter Tabuns.

"The same premier who said you can't legislate good will is now acting as if he can," he said in a statement.

But the showdown with teachers has helped the Liberals reach agreements with other public sector workers.

The Ontario Public Service Employees Union, which represents 38,000 public servants, announced Wednesday that it had struck a two-year tentative agreement with the province.

The government said it included a commitment to implement a two-year wage freeze, but details won't be released until the agreement is ratified. Those votes are scheduled for Jan. 21-23.

It's not a perfect agreement and OPSEU members may not like it, said union president Warren "Smokey" Thomas. But it was the best deal they could make when the government seemed "very willing" to legislate contracts.

"In our opinion, it's better to bargain something than have it imposed," Thomas said. "Frankly, if it had been imposed, both sides usually end up being pretty unhappy."