TORONTO - School bus drivers employed by First Student Canada in southern Ontario have given their union a strike mandate to back contract demands.

The Canadian Auto Workers Local 4268 says the vote to support a strike, if necessary, received "overwhelming" support.

The union represents about 750 school bus drivers who work for various school boards and customers in southern Ontario.

It says there has been little headway in talks over the last six months.

No strike date has been set but the mandate expires March 30, and the union says a strike notice could be issued at any time before that date. The union has been in a legal strike position since December.

A major issue, according to the union, is drivers being asked to perform extra tasks for which they are not being paid.