London Underground services returned to normal today after the travel chaos caused by a 48-hour walkout by thousands of Tube workers, but the capital now faces a postal strike.
The Communication Workers Union announced that up to 10,000 of its members will take action on June 19 after claiming that the Royal Mail was pressing ahead with "arbitrary" cuts in jobs and services.
Deputy general secretary Dave Ward said: "There is growing unrest across the country as Royal Mail tries to impose damaging cuts and changes without the input of union reps. The future of the business must be safeguarded through careful planning, not shooting from the hip."
Business Secretary Lord Mandelson said the strike was "highly regrettable" and typical of the problems Royal Mail was facing, adding: "Striking is not the solution. The Royal Mail needs urgent reform and this will only happen if the CWU co-operates in making it happen."
A Royal Mail spokesman said: "The CWU's threat to customers of damaging strike action in London is completely at odds with its repeated claim to support modernisation and to introduce new ways of working throughout the business.
"In May, the union stated its belief that investment in, and the pace of, modernisation needs to be stepped up and we urge them to act accordingly and not to call our people out on strike action which can only hurt our customers and damage our drive to build a strong and sustainable future for Royal Mail, and to protect the universal service in the competitive marketplace."
Workers in all areas of deliveries, collections and processing across London will take part in the strike and the union warned that further industrial action would be taken if the dispute was not resolved.
Meanwhile, Transport for London said there was a good service on all 11 Tube lines today, bringing relief to millions of commuters who suffered huge delays getting to work in the past two days.
Members of the Rail Maritime and Transport union returned to work at 7pm last night, although fresh strikes could be called if the row is not resolved.
Both sides will return to the conciliation service Acas next week for new talks in a bid to break the deadlock, with agreement on job losses the main sticking point.
London's Mayor Boris Johnson said he hoped a deal could be agreed, adding: "I think there's a very good deal to be done and I very much hope the RMT leadership will take it."Reuse content