TORONTO -- Almost 5,000 elementary teachers in one of Ontario's largest school boards are expected to take strike action Monday as labour strife in the province continues to ramp up.

Teachers in York Region, which includes 120,000 students in nine municipalities north of Toronto, are starting the first stage of an "escalating withdrawal" of administrative services, said David Clegg, president of the York Region Teacher Local.

"It's aimed at the minutia that the ministry has created for teachers to work with, and that will stop and provide teachers the opportunity to spend more time teaching and less time filling out paper for the Liberal government," he said.

On Monday and Tuesday, teachers won't be arriving until 30 minutes before class starts and will leave no later than 30 minutes after students are dismissed for the day, he said.

Teachers aren't being told to withdraw from grading or marking, and will still participate in parent-teacher interview days.

The Elementary Teachers' Federation of Ontario, which represents the teachers, advised all of its members about a month ago to write only the bare minimum on report cards.

Other union locals will soon be able to take strike action as well, said ETFO president Sam Hammond.

Teachers in two or three other school boards in eastern and northern Ontario will be in a legal strike position later this week, he said. All their 76,000 members will be in a legal strike position within two-and-a-half weeks.

Last week, Ontario Secondary School Teachers' Federation announced teachers at 20 boards across the province, including Toronto, Ottawa, Niagara and Thunder Bay, would take strike action after talks with the province collapsed.

The high school teachers' union said Saturday it has reached a tentative agreement with the York Region District School Board, and a deal has also reportedly been reached this weekend between the union and the Upper Grand District School Board in Guelph.

OSSTF, which represents 60,000 members, and ETFO are protesting the Liberal government's new anti-strike law, which also cuts benefits and freezes wages for most teachers.

Education Minister Laurel Broten said she's disappointed that ETFO is moving ahead with strike action, but warned that the legislation gives her the tools to stop it.

"For instance, we could bring forward an order-in-council to prohibit the specific action which is causing student safety to be compromised," she said Friday in a statement.

"We will monitor strike action very closely with a specific focus on student safety."

Premier Dalton McGuinty and Broten promised parents that the school year would be free from labour strife if the legislation passed. But they're not using their new powers to stop the strike action, said Progressive Conservative education critic Lisa MacLeod.

"As a parent, it concerns me," she said. "My daughter is in elementary school. You worry about the safe conditions if there is not adequate supervision in the playground, in the schoolyard."

It's clear the Liberals aren't using their legal authority to stop the strike action because they're trying to win back the support of teachers during the leadership campaign, she said.

"They can either do what they promised the legislature they would do -- which would be an academic year without any labour problems -- or they can sit on their hands and play tough to the public while they play nice with their union buddies," MacLeod said.

Broten said unions still have until Dec. 31 to bargain new contract agreements with local school boards based on the province's earlier deal with Catholic teachers.

She urged ETFO to keep negotiating with local school boards rather than resort to strike action.

But Hammond said the government won't negotiate with ETFO to find a way to break the impasse.

Government officials abruptly cut off talks a week ago and haven't invited ETFO back to the table since then, even though he's willing to meet with them, he said.

If the government forces teachers to go back to doing the tasks they've withdrawn and there's no hope of negotiating a solution, teachers may have no choice but resort to a full-blown strike, Hammond said.

"We will have no option but to escalate the implementation of our rights under the Ontario Labour Relations Act," he said.

The Liberals were warned from the start that their constitutionally-challenged legislation would create conflict in Ontario schools, said NDP education critic Peter Tabuns.

They didn't just shoot themselves in the foot, "they've hurt children and families as well," he said.

"The minister and the premier have to get back to the table with teachers and education workers."