The clock is ticking on possible strike action by public high school teachers at the end of April.

Seven school districts that could be affected by possible strike action include three in the GTA: Peel, Halton and Durham. Catholic high schools would not be affected.

The public secondary school teachers’ union said Tuesday that Peel, Halton and Durham have requested their “no board” reports, which effectively start the timeline toward a possible withdrawal of services.

According to Paul Elliott, president of the Ontario Secondary School Teachers Federation, Halton has received its no board report.

Once a no board report has been issued and received, negotiating parties must achieve a deal within 17 days or the union is in legal strike position.

The OSSTF says its teachers and support workers have been without a contract since last August.

Talks continue at both the local and provincial level.

With files from CTV Toronto’s Naomi Parness