More than 200,000 households could face delays to their boiler repairs during some of the coldest weeks of winter as the GMB union calls to resume its British Gas strike from Friday. The union has called on its members working as field engineers for Britain’s largest energy supplier to down tools for another five days as part of a nation-wide response to the company’s “fire and rehire” plans. The GMB says the latest strike action will add to a backlog of 170,000 boiler repairs and 200,000 delayed service visits, ahead of a cross-party parliamentary inquiry on the dispute scheduled for Tuesday. A statement from British Gas said it had strong contingency plans in place and would prioritise vulnerable households and emergencies. The GMB’s national secretary, Justin Bowden, said the company’s claim to be catching up on the work was bogus and that a protracted dispute was looming. Bowden will face the business, energy and industrial strategy select committee on Tuesday to answer MPs’ questions alongside Chris O’Shea, the chief executive of British Gas’s parent company, Centrica. The GMB called a 12-day day strike last month after balloting its 9,200 British Gas members. Around 59% took part in the vote, of whom 89% – or 4,830 workers – voted in favour of industrial action. About 80% of Centrica’s 20,000 staff have agreed to sign up to the new employment contracts. GMB’s call to down tools followed months of tense negotiations between its representatives and Centrica over its plans to reduce its workforce and shift employees on to new contracts. The union has accused Centrica of “bullying” its 20,000 employees into accepting worse employment contracts or losing their jobs as part of a “fire and rehire” plan. The embattled FTSE company, which has lost more than three-quarters of its market value in the last five years, said the decision to ask all employees to sign up to new employment contracts was always a “final resort option”. “Our business needs to change to survive and protect 20,000 jobs,” a spokesperson said. “We know change is difficult but we have offered a fair deal that has been negotiated over 300 hours with unions where base pay and pensions are protected.”