Teachers at a junior school are to hold two more strikes next week.
Uplands Junior, in Highfields, Leicester, shut for a day last month when members of the National Union of Teachers (NUT) took action over proposals by the governing body to axe eight teaching assistant posts at the end of term.
Now union leaders have announced another two days of strikes, on Tuesday and next Thursday.
It is expected the school will have to shut on both days.
Staff at Uplands Junior lodged a formal grievance in March against head teacher Tim Luckcock and chairman of governors Abid Matak over a number of issues, including the redundancy proposals.
Union leaders, the local authority and governors have agreed to an independent investigation into the grievances, but not on who should carry this out.
Independent conciliation service Acas had been suggested by the local authority, a proposal accepted by the union.
Ian Leaver, assistant secretary for Leicester's NUT branch, said: "Despite our efforts, the governors have failed to agree on an investigator."
The governors said they were taking legal advice to ensure any decisions were in the best interest of the school.
Mr Leaver said: "The situation is deteriorating, with staff now choosing to leave for other jobs.
"There could be a shortfall when pupils return in September and that could seriously affect children's learning.
"It could be very difficult to attract people to work there, given the current situation.
"We're taking this action very reluctantly and would urge the city council to suspend the head teacher while an investigation takes place and remove the governors.
"No-one wants to see a good school like Uplands destroyed."
Margaret Libreri, council director of learning services, said: "We're confident we are now extremely close to reaching agreement on the grievance investigation arrangements.
"The intention is to begin this on June 10.
"Local authorities do have the power to issue formal warning notices to governors, or to remove governors in exceptional circumstances, but it's better if we can work with governors to get the investigation started.
"It's in the best interests of the children these matters are resolved before the end of term."
Mr Luckcock was unavailable for comment yesterday.
Mr Matak said he was "disappointed" to hear of further strike action, saying it would cause "disruption" to pupils.
He said: "Given the legal obligations on governors, we can't make decisions in respect of the grievances and complaints until there is a full investigation and outcome.
"Further, because of the nature of the grievances, it's necessary to seek independent legal advice."
