Royal Mail workers have voted overwhelming against the government's controversial plan to sell off the 497-year-old postal service.
More than 96% of postal workers who voted opposed the privatisation despite the government promising them each about £1,500 in shares as part of the flotation plan.
Billy Hayes, the general secretary of the Communication Workers Union (CWU), which organised the ballot of 112,000 Royal Mail staff, said: "No one has yet asked postal workers what they think about privatisation. Today postal workers have spoken loud and clear.
"The workforce does not support the government or Royal Mail on selling the company. This company is flourishing in public ownership as the recent doubling of profits proves."
Business minister Michael Fallon has promised that workers will collect at least 10% of the shares in the privatisation, which could generate up to £3bn for the government.
Dave Ward, the deputy general secretary of the CWU, said postal workers would not "sacrifice their souls for a so-called 10% stake when they know their jobs, pensions and conditions are once again under threat".
Royal Mail workers also voted nine-to-one in favour of a boycott of delivering competitors' mail. But the company took the CWU to the high court on Wednesday to seek an injunction to prevent the boycott. A judge will make a ruling next Friday.
The company warned employees that a boycott could result in a significant loss of business.
Royal Mail accepts letters and parcels at its mail centres that have been partially sorted by large customers and other postal operators, and delivers them to 29m homes and businesses for an agreed price. "Royal Mail is required by law to allow access to our network and deliver all the mail we are asked to," a spokesman said.
The consultative ballot, which had a turnout of 74%, is likely to lead to a vote on strike action, which could severely damage the government's chances of securing a successful sale. Some potential City shareholders have already let it be known that they will not invest in Royal Mail because of the threat of industrial action.
Fallon said he was disappointed with the CWU's vote. "I'm focused on what's best for Royal Mail's employees, customers and the taxpayer," he said. "I want to implement a share scheme that will give employees a real stake in the company as they were promised two years ago. I urge the union to continue to engage on our plans for Royal Mail.
"Our plans are not new. Parliament debated and backed our intention to sell shares in Royal Mail more than two years ago. Everyone agrees that Royal Mail needs to change if we are to protect the future of the six-day-a-week one price goes anywhere service. To do so, Royal Mail needs future access to private sector capital to meet the challenges of a changing postal market and to take advantage of opportunities such as the boom in on-line shopping."
Royal Mail said privatisation would enable the company to "combine the best of the public and private sectors and secure as many good quality jobs as possible".
"The UK government has made it clear it does not have the capital itself to invest in Royal Mail. It wants that capital to come from the private sector," a spokesman said.
The company said privatisation would not affect employees' terms and conditions.
