Postal staff across the UK went on strike today ahead of a national ballot planned for next week.
The ongoing dispute over jobs, pay and services continues unabated, with deliveries affected in areas where industrial action is taking place.
According to the Communication Workers Union, the dispute is the biggest with Royal Mail since the national strike of 2007 and has led to a backlog of undelivered post.
Royal Mail played down the scale of the problems, saying in a statement: "The vast majority of deliveries are taking place as usual today all over the country and, with 90 per cent of our people working normally, Royal Mail is doing all we can to minimise disruption to those customers in the areas which have experienced industrial action."
Strikes have taken place at a local level since June and have continued throughout the summer.
Today, drivers staged a 24-hour walkout from 4am in locations including Birmingham, Bridgend, Carlisle, Coventry, London, Northampton, Warrington, Glasgow, Swindon, Bristol and Leeds, the CWU said.
A number of delivery offices in south-west London also took action, in addition to Rochdale.
Postal services are set to be hit by a fresh wave of strikes next week, starting with delivery offices in Cambridgeshire on Monday.
Members of the CWU will start voting on Wednesday on whether to back a nationwide walkout, with the result expected on September 30 - while Labour is holding its annual conference.
Royal Mail attacked the decision to press ahead with the ballot as "wholly irresponsible", as talks between senior management and the union leadership were still being held.
The CWU said earlier this week that more than 20 million items of mail were backed up in London, one million items in the Bristol area, half a million in Peterborough, and a quarter of a million in Leeds.
Deputy general secretary Dave Ward said: "Royal Mail's head-in-the-sand approach to the problems in the mail industry is now severely damaging services for customers, with backlogs bigger than in the national strike of 2007."
Paul Tolhurst, Royal Mail's operations director, said: "We urge the CWU to abandon strikes and the threat of strikes, and focus on providing customers with the service they need and expect, rather than planning to hurt them with the threat of more strikes."Reuse content