LONDON, Ont. - The Thames Valley District School Board (TVDSB) has announced they will close all schools Monday unless progress is made in bargaining with members of the Canadian Union of Public Employees.

The London District Catholic School Board has decided to do the same.

“We recognize the significant impact this has on families, staff and our school communities,” says TVDSB Director of Education Mark Fisher, in a news release.

In the public board, CUPE represents custodians, educational assistants, clerical staff, technical support, early childhood educators, custodians and maintenance employees.

Associate director of the TVDSB, Jeff Pratt, spoke to CTV News Thursday night, where he made the situation clear to parents, should no agreement be reached in last minute talks.

“All school sites will be closed to students.”

Pratt says the decision must be made to protect student safety.

With 3,400 members potentially on strike, representing a third of the staff for TVDSB, Pratt says schools cannot be operated safely.

Further, he says, “We would not be able to keep our schools clean…We would not be able to supervise all of our students without our educational assistants and early childhood educators.”

One school board operating in London says its schools will be open on Monday.

The Conseil Scolaire Viamonde has three full French-language elementary schools, and one high school, in the Forest City.

In a release, it says, because only janitorial staff are represented by CUPE, its staff will operate schools.

However, parents and visitors are cautioned they may encounter picket lines if dropping students off at schools.

The Conseil Scolaire Catholique Providence, the region's other French-language board, has only said it will keep parents informed, but released no details about closures as of Thursday evening.

Hundreds of Ontario schools set to close

Across the province, there may be half a million students out of the classroom if education workers follow through on strike threats.

The Toronto District School Board - Canada's largest, with 250,000 students- was among those to issue a notice to parents Thursday afternoon informing them that if there is a labour disruption, schools will not open.

The Peel District School Board and York Region District School Board, the province's second and third largest boards with a combined total of more than 282,000 students, have said they would also close in the event of a strike.

CUPE, which represents 55,000 custodians, clerical workers and early childhood educators, gave notice Wednesday of the potential for job action.

The Toronto and Peel boards cite student safety as their main concern, while the York board says it is not a decision made lightly.

CUPE launched a work-to-rule campaign on Monday but is returning to the bargaining table with the province and school boards Friday afternoon for weekend talks.

- With files from The Canadian Press