Liverpool mayor Ned Mannoun has been accused of "industrial scale" bullying and intimidation against the council workforce in explosive documents filed by the union for council staff.
The United Services Union (USU) says around 600 Liverpool council employees have been left fearful for their safety and livelihoods by repeated public threats of sackings and ongoing instability.
It filed the application for a stop bullying order in the Industrial Relations Commission on Thursday, just days after councillors mulled plans that could have led to the termination of 140 workers and entire departments.
"Workers at Liverpool Council should not have to come to work every day wondering whether politicians are going to publicly threaten their jobs again," USU general secretary Graeme Kelly said.
"This is not robust debate. This is psychological warfare being waged against ordinary workers who are trying to serve their community."
Mr Mannoun has been contacted for comment.
The legal action is believed to be the first time a sitting mayor has been accused of bullying an entire workforce rather than individual workers, according to the union.
It centres on public comments made by Mr Mannoun that the union claims have put council workers in danger by stoking community resentment against them.
The union highlighted a video he posted on Facebook in April, which depicted council workers with the caption "Liverpool Council Union employees attack Muslim mayor with Islamophobia and anti-Semitic chants and bring pig to protest".
The video paints Liverpool council union members as racist and a threat to the community, USU alleges in court documents.
Council staff have reported being shot at and harassed by members of the public amid the ongoing turmoil.
A USU survey of union employees found more than half of respondents had considered leaving the council as a result of the conduct of the mayor and councillors.
The claims come as Liverpool City Council awaits the findings of a public inquiry into allegations of maladministration and a toxic work environment.
If the findings are adverse, the council could be placed into the hands of an independent administrator administration by the NSW Office of Local Government.
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