The telecoms giant is facing its first national strike in 34 years after the Communication Workers Union (CWU) announced plans to ballot its members on industrial action.

The CWU represents about 45,000 BT Group staff and the ballot will cover workers at BT, EE and Openreach. It could lead to walkouts in the spring – when many people will still be working from home and reliant on their broadband.

The CWU says the action is necessary due to “an unprecedented and sustained assault on job security and hard-won terms and conditions.”

The CWU described BT’s senior management team as “belligerent” and accused it of spending more than a year “pursuing a brutal and needlessly confrontational agenda” and not being willing to “negotiate meaningfully”.

Andy Kerr, CWU deputy general secretary, said: “We didn’t pick this fight. In fact we’ve provided management with every possible opportunity to step back from the brink, consistently offering to work in partnership with the business to address whatever challenges it faces – just as we’ve done on numerous occasions over the decades since privatisation.

“What we’re not prepared to accept, however, is seeing members’ cherished job security and Ts&Cs being attacked on multiple fronts – with longstanding colleagues being picked off one by one, simply because a new breed of management wants to stamp its mark by making compulsory redundancies as a matter of warped principle.

“If BT don’t want us to ballot then they can have us back round the negotiating table just as soon as they want. Our door is still open, and we want to resolve this dispute, but this will require a huge shift in attitude from the company.  At this point in time that doesn’t look as if it’s going to happen – and that’s why we’re gearing up to fight.”

According to the union, BT wants to close hundreds of sites across the UK over the next few years and concentrate the majority of its operations at 30 key locations. The move will involve compulsory redundancies, as well as changing the contracts of staff who remain employed.

If the strike goes ahead the national strike action would be the first by BT since 1987 when about 117,000 engineers walked out over the refusal to reinstate engineers suspended during a dispute over pay and working conditions.

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.”