About 115,000 postal workers at Royal Mail are to stage a 24-hour strike on 16 February in their continuing dispute with management over pay and conditions.
The strike will affect all shifts for 24 hours from 12.30pm that day, the Communication Workers Union (CWU) said.
The union said it had called the strike after Royal Mail began forcing through unagreed changes to work practices at offices across the country.
The CWU added that these changes directly contravened the industrial relations framework between the union and Royal Mail, and that they remove the right of the union to negotiate at a local level.
Dave Ward, the CWU general secretary, said: “This action is down to the conduct of Royal Mail management, who have displayed a complete lack of integrity.
“Our members will not just sit back and watch as their working lives are destroyed by a company leadership hell-bent on ripping up historic arrangements that protect their rights and give them a voice through their union.”
It is the latest move in what has become a bitter and protracted row between the union and Royal Mail over pay and working conditions.
Royal Mail expressed disappointment at the move, and said it remained committed to talks. It urged the union to withdraw the strike “for the good of our customers and our people”.
A Royal Mail spokesperson said: “We entered facilitated talks through Acas in good faith, believing that the CWU were serious in their claim that they wanted a resolution. In announcing further damaging strike action, the CWU have shown they are not interested in resolving this dispute and continue to focus on damaging out business further.
“The CWU’s misguided belief that further industrial action will remove the need for change and force an improved offer, is misleading its members and risking their long-term job security.”
Royal Mail’s chief executive, Simon Thompson, has come under attack for his handling of the dispute from his predecessor Rico Back. Back claimed that Thompson lacked experience and had mishandled talks with the CWU that led to strikes and chaos in the run-up to Christmas.
Thompson faces a rare recall to parliament to answer more questions from MPs over the accuracy of evidence he gave to the business select committee last month in a sometimes testy exchange.