Unions say there is a “culture of bullying, harassment and racism” at Hackney Council and one has threatened possible strike action unless there is a full independent investigation.

Unite, Unison and GMB – which between them represent thousands of council workers – have sent an explosive 18-page document to all councillors and union members alleging a host of serious issues, particularly at Hackney Service Centre, the call centre behind the town hall.

The allegations include:

• Workers’ complaints about discrimination being swept under the carpet, or resulting in them being punished for speaking out;

• A black female worker being called a member of the Taliban by a white, male colleague, who also said he would “start embracing his roots because he was white and whites used to enslave black people”;

• A manager disclosing, in front of another manager, that a black female agency worker had been a victim of domestic abuse, shouting at her: “Your partner is always pulling your hair out and you’re a walking car crash,” and: “There is always drama with you”;

• A senior white male manager making “well-known racist stereotypical comments to black staff”.

It comes as Hackney Council, which prides itself on being a progressive employer and force for good, is embroiled in an employment tribunal brought by Unite representative Natasha Johnson.

As reported by the Gazette last month, Natasha, who has learning disabilities, claims she was the victim of racist, sexist and disability discrimination. The hearing has been adjourned until later this month, but last week Natasha was sacked.

She had been one of the leading Unite members helping organise workshops last year to tackle “growing concerns and complaints of bullying, harassment and discrimination within Hackney’s workforce”.

Those workshops were backed by Unison and GMB as well as more than 500 workers – and agreed to by the town hall.

But they were postponed when Natasha was suspended a year ago. The suspension came while Natasha was going through a disciplinary and shortly before she was set to appeal over a grievance she had made about “management victimisation, harassment, bullying and racial and sexual discrimination”.

Unite says the fact she was subject to a disciplinary and dismissed highlights the culture within the workforce regarding staff who make complaints.

It wants a full independent probe into the service centre covering all complaints made within the last two years regarding bullying or discrimination of any kind.

The letter sent to councillors calls on them to consider:

• A meeting with employment chief Cllr Carole Williams and the unions;

• Reinstating Natasha and seeking a settlement of the outstanding tribunal. It adds: “The council must make clear that workers can come forward and report harassment and be safe from persecution”;

• Supporting the union’s demand for a fully independent investigation into the service centre.

The union’s demands have been backed by Hackney South and Shoreditch MP Meg Hillier, who said: “Bullying should have no place in a workplace and needs to be called out. I am pleased that employees have such strong trade union support.”

The letter also references the Crawford Report, an independent investigation by lawyer Lincoln Crawford commissioned in 1996 in response to allegations of racism. Mr Crawford found there was a blame culture in which visible minority staff were blamed for everything and scrutinised more than others.

He found there was a lack of confidence in the grievance structures, with some complaints not investigated at all, and he concluded managers were supported at all cost.

He also said of the legal department’s failures: “There appeared to be a permanent suspicion that all race discrimination claims were bogus.”

Unite region manager Onay Kasab said: “Hackney Council has made clear if you report racism, sexual harassment or bullying you will be dismissed. That’s the message this sends out.

“What Unite will now be doing is consulting our members about what action, including the possibility of industrial action, will be taken. Not just in defence of Natasha but the rights of individuals to stand up and make complaints.”

Hackney Council did not respond to a request for comment.