CWU says Royal Mail workers 'certain' to back strike
The general secretary of the the Communication Workers Union (CWU) has said that a strike ballot of postal workers will lead to industrial action.
Billy Hayes told The Andrew Marr Show that he was "absolutely confident" of a yes vote.
The union is unhappy about privatisation plans, as well as a current pay offer.
The outcome of the ballot will be announced on 3 October, with strikes possible seven days after that.
The current proposal from Royal Mail gives staff a pay increase of 8.6% over three years.
This is the first nationwide strike ballot for Royal Mail workers since 2009.
After the ballot was announced, Royal Mail chief executive Moya Greene, said that she still hoped to reach an agreement with the union.
"Talk of a ballot for industrial action makes no sense when there is a significant three-year deal on the table and negotiations are ongoing," she said.
While Mr Hayes argued Royal Mail did need investment, and faced increased competition for parcel deliveries from the likes of TNT, he insisted that privatisation was not the best option.
"Privatisation will damage our postal service," he said.
He added that in terms of support from the union for a strike, and his opposition to privatisation, he was "very confident in our position."
Scottish First Minister Alex Salmond on Sunday called for a moratorium on the privatisation of Royal Mail until after the independence referendum.
He told the BBC's Sunday Politics Scotland programme: "I want a moratorium on the sell off of the Royal Mail to allow the people of Scotland, when they vote next year, to come to a decision on whether that national asset should stay in public hands or be hived off as the London government intend to do at the present moment."
The government last week gave formal notice to the stock exchange of plans to privatise the Royal Mail "in the coming weeks".
Shadow business secretary Chuka Umunna, speaking on the BBC's Sunday Politics programme said that Labour will not pledge to renationalise the Royal Mail.
Any such move would be "completely irresponsible" and "like writing a blank cheque" he said.
Under the privatisation plans, Royal Mail staff will get 10% of the shares. The public and institutional investors will be able to purchase the rest.
The minimum amount members of the public can buy in shares will be £750.
Free shares will be given to 150,000 UK-based Royal Mail employees, who will be able to apply for additional shares under an employee priority offer, with a minimum application of £500.
BBC business editor Robert Peston said he expected the sale to take place in November.