British Royal Mail with a history of hundreds of years is expected to hold an initial public offering (IPO) within weeks. British government announced on Thursday that it is pressing ahead with the plans to privatize the postal service company. It has given formal notice to the London stock exchange market on proceeding IPO. The Royal Mail was expected to be valued up to 3 billion pounds (4.74 billion U.S. dollars). Royal Mail staff, which was more than 150,000 in total, will be offered 10 percent of the shares for free, according to media reports. Retail buyers can apply for a stake with a minimum investment of 750 pounds (1,185 U.S. dollars). The privatization was expected to be the biggest by a British government since former Prime Minister Margaret Thatcher sold off former state-owned companies British Gas and British Telecom to the public in the 1980s. Margaret Thatcher had considered privatization of Royal Mail to be a step too far. Business Secretary Vince Cable said it was \"an important day for the Royal Mail, its employees and its customers\". However the privatization plan is opposed by the trade unions, which plans a strike action against the plan. The Communication Workers Union (CWU), which represents 125,000 postal workers in Britain, said on Thursday that \"the plans to sell are a betrayal of the British public, 70 percent of whom are against privatization according to a Sunday Times poll at the weekend.\" Billy Hayes, CWU general secretary, was quoted as saying that privatization would put jobs and services at risk and lead to higher prices for customers. \"We\'ve seen it happen time and again in other industries.\"