Postal workers are threatening weeks of disruption in the run up to Christmas with plans for 19 days of strikes in October and November.
Union leaders have launched a significant escalation in their industrial dispute with Royal Mail, warning of severe disruption to deliveries during popular shopping periods such as Black Friday, Cyber Monday and the run-up to Christmas.
Dave Ward, general secretary Communication Workers Union (CWU), which represents 115,000 postal workers, said: “This is a significant announcement, but it is one which matches the level of anger our members feel at the way Royal Mail Group has treated them.”
It comes after the Royal Mail last week terminated a string of agreements struck with unions since its privatisation in 2013, arguing that the CWU was using them to frustrate attempts to modernise the service and compete with parcel delivery services such as Evri and DHL.
A spokesman for Royal Mail added: “Royal Mail is losing £1m a day and must change faster in response to changing customer demands. We operate in a competitive market, and our customers have choices.
“Further strikes and resistance to transformation by CWU will only make our financial position worse, and threaten the long-term job security of our postmen and women. The CWU has a responsibility to recognise the reality of the situation Royal Mail faces as a business and engage urgently on the changes required.”
Mr Ward said: "The CEO of Royal Mail Group, Simon Thompson, is treating postal workers as if they are stupid.
"These are the same people that have kept the country connected and returned Royal Mail Group to record profit.
"Postal workers across the UK now face the fight of their lives to save their jobs and the service they provide to every household and business in the UK.”
Royal Mail chiefs on Tuesday night accused the CWU of refusing to turn up to arbitration talks.
A spokesman said: “On 22 September, Royal Mail invited CWU to enter into talks through Acas to find a resolution to our dispute on change and pay. This evening, rather than responding to our offer of Acas talks, the CWU announced further damaging industrial action, once again taking the path of prolonging disruption over resolution.”
The CWU is yet to publish the days it will instruct its members to walk out.
Mr Ward raised the spectre of concerted action by trade unions as leaders battle for better pay deals and oppose attempts to cut costs by changing working practices.
He said: "We call on everyone to stand with their local postal worker. If Royal Mail Group are allowed to get away with this then it sends a green light to every rogue big business in the UK.
"We will not stand by and see the Royal Mail Group become the next P&O but we need your backing.”
Rail unions will next week walk out after a truce was called by most trade unions during the period of mourning following the death of Queen Elizabeth II.
A spokesman for Royal Mail said: “We apologise to our customers for the inconvenience the CWU’s continued strike action will cause. We are doing all we can to minimise any delays and keep people, businesses and the country connected.”