British Gas engineers are to stage 12 more strikes in the long-running dispute over pay and conditions.

Members of the GMB union will walk out for four days from February 12, 19 and 26, with further action expected unless the deadlock is broken.

The engineers started four days of strikes on Friday in the latest wave of action this year.

The GMB said its 7,000 members have “stood firm” during 12 days of industrial action so far this year.

We have strong contingency plans in place to ensure we will still be there for customers who really need us, and we’ll prioritise vulnerable households and emergencies

The union is campaigning against new contracts it says will lead to pay cuts and longer hours.

British Gas maintains it is trying to avoid redundancies and stressed that basic pay and pensions are being protected.

The union claims the backlog of appointments caused by the industrial action has grown to 170,000, a figure the company disputes.

Justin Bowden, GMB national officer, said the company was pressing ahead with the new contracts, adding: “The majority of field staff are not prepared to accept the imposed cuts to pay and conditions.”

A spokesman for British Gas owners Centrica, said: “We have strong contingency plans in place to ensure we will still be there for customers who really need us, and we’ll prioritise vulnerable households and emergencies.

“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 – 83% of our employees have already agreed to the new terms.’’

Andy McDonald, shadow employment rights and protections secretary, said: “Threatening workers with the sack unless they agree to cuts to wages and conditions is a disgraceful practice.

“Recent industrial disputes have been resolved by employers withdrawing the threat of fire and rehire. British Gas must do likewise.

“The Labour Party repeats its call for the Government to outlaw ‘fire and rehire’ tactics which punish working people, penalise good employers, and damage our economy.”