The union maintain staff are not striking over job cuts or contract hours
Teachers at a school in Rotherham are on strike following the suspension of a colleague.
Head teacher of Listerdale Primary School, Craig Roberts, was suspended in September.
The Children's Academy Trust said the suspension followed "serious concerns of a non-safeguarding nature".
The National Union of Teachers called the suspension of their member "unreasonable" and "unjustified."
The trust said an "independent formal investigation" was in its final stages and the suspension would remain in force until it had been completed.
ACAS claim denied
The school, on Beech Avenue, is closed for over more than half the pupils and only children from years one, two and three are in lessons.
In a statement, the trust said teachers would strike on Wednesday and Thursday, but Nick Raine, regional officer for the NUT, said they planned to take action for another week.
He said head teacher Mr Roberts was suspended at a school meeting, without warning, and the NUT believed the action had been taken to "deny the member access to union representation."
The NUT also claim the trust refused to attend talks with the government's Advisory Conciliation and Arbitration Service (ACAS) but this has been denied.
The Trust said it had written to the union offering to meet and involve ACAS, but said there had been no response to date.
Listerdale Primary School converted to academy status in November 2014
