As the Ontario public elementary school teachers' work-to-rule campaign continues, the province's education minister says some union leaders are instructing teachers to "delete" report-card related information that's been compiled since the last report cards were sent home.

The work-to-rule action, which was announced in April by the Elementary Teachers' Federation of Ontario, means teachers are not performing certain administrative duties. That includes writing comments on report cards and entering grades in a report card system.

The union, which represents more than 76,000 teachers, occasional teachers and education professionals in Ontario, has previously said the withdrawal of services will continue until a deal has been reached with the school boards.

On Tuesday, in response to the instruction, Ontario's Education Minister Liz Sandals sent out a letter to school board chairs, stressing a need for some form of "final communication" that will be handed out to students and parents -- even if it's only a pass or fail letter.

"While my hope is that there will be capacity to produce a report card with student's grades but no comments, I understand that there may be only be capacity to produce a letter of promotion," Sandals said in the letter.

"While school boards will have the flexibility to decide what works for them and their students at the local level, board should prioritize providing more detailed information or grades to students transitioning from one school to another (e.g. Grade 5 and/or 8 students)."

Sandals also told CTV Toronto that this latest instruction from some union leaders to delete information will affect a number of school boards across the province.

"I've seen directives from a number of boards around the province," she said. "So it's not just a GTA issue. I've seen the direction to delete … certainly in three boards."

Sandals is also encouraging parents to set up face-to-face meetings with teachers before the school year wraps up in order to get an update on their child's performance.

The work-to-rule campaign affects more than 900,000 students.

Earlier this month, school boards across Ontario said they were exploring options to have grades entered on reports by hiring people.

With a report from CTV Toronto's Paul Bliss