The move comes just weeks before the government's review of the postal service is due. The report, conducted by the former deputy chairman of Ofcom Richard Hooper, is widely expected to highlight the unsustainable nature of the current mailing model.

Hooper was quoted in The Telegraph as having said that "maintaining the status quo is not an option".

Speaking to the Financial Times, Mandelson said the change would have taken place in 1998, saying: "If I had not been forced to resign, it would have happened."

Partial privatisation of the Royal Mail, which is currently burdened with a massive pensions deficit, "could produce a much-needed injection of funds leading to a more effective service," according to Andrew Brown, director of corporate affairs at the BPIF.

He added: "Modernisation is a must, but that is not necessarily easy to achieve. Time will tell."

Earlier this year, postal regulator Postcomm put its weight behind the partial privatisation of Royal Mail, arguing that access to private capital and a stronger set of incentives were needed to help it restructure and become more profitable.