BRITISH Gas workers could strike over the festive season as a dispute over new contracts escalates.

Thousands of GMB members will vote on whether to take industrial action, although the union pledged to avoid leaving the elderly and vulnerable without heating.

British Gas owners Centrica confirmed that negotiations on terms and conditions have ended, adding that a revised proposal has been put forward.

The company said that it has lost more than one million customers in two years, with many choosing lower-priced products from competitors.

It added that it has lost over half its earnings over the past 10 years.

The company claimed that it had “no choice” but to make changes to its terms and conditions to modernise and win back customers from competitors.

But GMB accused the company of threatening to sack 20,000 workers and then re-employ them on inferior pay and conditions if they do not accept changes now.

An indicative ballot in August showed that most members would be in favour of industrial action if there was a vote.

GMB national officer Justin Bowden said: “British Gas issued an ultimatum in July to fire and rehire 20,000 workers in the middle of a national health emergency.

“GMB warned them that members were angry, with a 95 per cent vote for action in August.

“We sought to get the threat off the table. The best that they were prepared to do was postpone the ultimatum until January.

“This is an insulting response to these essential workers keeping homes across the nation heated in the depths of winter.

“Anger has boiled over as members have now seen the full proposals and how they impact them.

“GMB has responded by giving the go-ahead for an official national strike ballot. We will shortly announce the dates for the ballot.”