A row over jobs and site closures at BT (BT-A.L) could result in its first national strike in more than 30 years.
Workers at the telecoms grid are set to vote on industrial action over jobs, which could trigger the strike.
The Communication Workers Union (CWU) has said that 45,000 members in BT, Openreach and EE will be balloted. A "yes" vote will have a "massive impact" on the network, they warned.
The union said it was a response to an "unprecedented and sustained assault on job security and hard won terms & conditions."
In release on the CWU website on 11 March the group said: "Barring a dramatic eleventh-hour about-turn by a belligerent new senior management team which has now spent more than a year pursuing a brutal and needlessly confrontational agenda – despite incessant union appeals for meaningful talks to avert a full-scale industrial relations meltdown – that ballot will cover every part of BT, Openreach and EE where the CWU is recognised for collectively bargaining purposes."
The dispute over compulsory redundancies and the closure of sites, has been running for over a year.
CWU deputy general secretary Andy Kerr said: “This is a decision we did not want to take.
“Last year, our members delivered a huge yes vote in a consultative ballot, but BT Group are still in denial.
“We want to assure businesses and the public that we do not want to see disruptions to services. This action is about protecting our members, but also it is about protecting the service they provide to homes and businesses.
“My message to BT Group is that our door is still open, and we want to resolve this dispute, but this will require a huge shift in attitude from the company.
“My message to our members is to continue supporting their union and prepare to deliver a massive ‘yes’ vote.”
A BT spokesperson said, "We’re disappointed that CWU is contemplating industrial action, though the union has not started the formal industrial action process. We remain committed to discussing the concerns they have raised.
“BT needs to go through a period of immense change and investment to modernise itself for the future. Once complete, we will have a much simpler operating model with fewer people and we’ll be better able to serve our customers. Such change is always difficult – that’s why we have been discussing our plans with the unions and will continue to do so."
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