NASUWT union members at Whickham School and Sports College in Gateshead were set to strike on Wednesday of this week.
They are fighting management plans to transform the school into a privately-run academy.
Graham Dawson, NASUWT national executive member for the North East, said teachers felt they had been “misled”.
He said, “Teachers were told in March the school was not planning on submitting a bid [to become an academy] and, just a few days later, an application was made.”
Meanwhile the NASUWT is balloting teachers at Perry Wood Primary and Nursery in Worcester for strikes against plans to privatise it.
Governors at Kingsbury High School in Brent voted last week to press ahead with academy plans—despite widespread opposition. Some 85 percent of workers voted against the plans in a ballot organised by governors.
The NUT, ATL and NASUWT unions say they will ballot for action.
The NASUWT called off a planned strike against academies at Diss High School. Teachers won assurances on pay and conditions and so have called off the dispute. The school will become a privately-run academy in September.