The threat of industrial action by workers at gas giant Centrica has come a step closer in a row over jobs and pay.

Members of the GMB union at the company, and contractors PH Jones, voted by 95% in favour of having a formal strike ballot, which is set to be held in the autumn.

The union said on top of plans to make thousands of staff redundant, Centrica wants to change pay and terms and conditions that will have a detrimental effect for most of its 20,000 workers.

The GMB said it was told a fire and rehire plan was an “insurance policy”, with statutory notices on redundancy issued which say the process could begin at the end of November.

National officer Justin Bowden said: “Centrica bosses are holding a box of matches and threatening to set fire to the terms and conditions of this loyal and dedicated workforce. It’s a complete and utter betrayal of the British Gas and PH Jones brands.

“The company have already burnt through the confidence of its staff. Today’s vote demonstrates GMB members are not prepared to tolerate fire and rehire threats and are determined to have their own ‘insurance policy’ too.

“British Gas was an historically proud British institution but Centrica’s beleaguered management are betraying a once great brand and their entire workforce.

“Centrica’s problems were not caused by the loyal engineers, call centre workers and back office staff who have done everything asked of them over years of boardroom mismanagement, but yet again it’s their jobs that are in the firing line.

“GMB members have spoken loud and clear in delivering their verdict, now it’s time for the company to listen and get real.”

A Centrica spokesman said: “We know that change can be very difficult and we are doing all we can to support our people but we urgently need to act now to win back customers, grow our company and protect more jobs in the long run.

“We are committed to reaching a negotiated settlement this year which sets us up for future success, and we hope our unions, who have also agreed that change is needed, share that desire as we continue our ongoing negotiations.

“Our colleagues’ base pay and pensions will be protected, but simplifying and modernising working practices and their terms is essential if we’re to become more flexible in delivering for our customers, giving them what they want, when they want it, at a price they’re willing to pay.”

Unison members who work in Centrica offices have also overwhelmingly agreed to support moves towards an industrial action ballot.

National officer Matthew Lay said: “The business clearly faces challenges and we’re willing to negotiate to find a way forward.

“But Centrica’s provocative action in sending out fire-and-rehire notices was totally unnecessary and have enflamed the tensions in the workplace.

“It also raises questions about how the business values its workforce. The notices should be withdrawn to allow a solution to be found. Staff have spoken clearly today and the business must listen.”