TORONTO -- Ontario's high school teachers have reached a tentative contract extension with the Liberal government, the last education union to do so.

Paul Elliott, president of the Ontario Secondary School Teachers' Federation, says the deal extends the current contracts for teachers and support staff by two years.

If all of the contract extension agreements with teachers and support staff across Ontario are ratified, it means the Liberal government will avoid contentious education bargaining ahead of next year's election.

The contracts were set to expire this August, and the new agreements extend them to August 2019.

The last round of negotiations with the education unions saw support staff and elementary teachers staging work-to-rule campaigns and the government threatening to dock their pay.

Ontario's French teachers and education workers represented by the Canadian Union of Public Employees have ratified their two-year contract extensions, with English Catholic teachers, elementary teachers and other support workers still to vote on their tentative deals.