Con-Dem ministers ignored huge public opposition to Royal Mail privatisation and have given the green light to a November fire sale.

Tory Business Minister Michael Fallon was given a roasting by MPs as he announced that chunks of the world's oldest postal service will be flogged to private investors as soon as possible.

"This sale of shares will complete the final part of our reform of the postal sector," he declared, claiming: "Our reforms have put Royal Mail on the road to sustainable health."

His remarks were met with derision in the Commons, where MPs predicted that vital delivery services will suffer and shares in the £3 billion company will quickly end up in the hands of unscrupulous multinationals.

"It was exactly the same in the late 1980s when all the public utilities except this one were sold off," said veteran Labour MP Dennis Skinner.

"It was to be a share-owning democracy. Almost without exception they are now entirely owned abroad - the only difference is the support of the lickspittle Lib Dems. What an absolute disgrace."

Trade unions condemned the announcement, which Unite general secretary Len McCluskey said was "driven by blinkered right-wing dogma that has ridden roughshod over public opinion.

"Undoubtedly this will provide handsome profits for the Tories' chums in the City who will benefit for arranging the sale - this privatisation will be early Christmas present for the spivs and profiteers.

"In three to five years a great British public service, owned by and run for the public, will be in the hands of hedge funds, whose purposes a ripped-off Britain knows all too well," he predicted.

Postal union CWU general secretary Billy Hayes, whose 125,000 members at Royal Mail are being balloted on strike action, said the sell-off was "the wrong decision.

"Privatisation 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."

The CWU has demanded that Labour pledge to renationalise Royal Mail if it wins the next general election.

Labour shadow business secretary Chuka Umunna suggested that the sell-off was "politically motivated" and was being rushed to plug a short-term hole in the government's finances left by Chancellor George Osborne's failed economic policies.

But Mr Umunna made no mention of Labour's own plans for the service.

Campaign for Public Ownership director Neil Clark said a public Labour pledge to renationalise Royal Mail would sabotage the stock market flotation by scaring off potential investors.

He asked: "Has privatisation improved Britain's railways or brought lower prices and better service to gas, electricity and water consumers?

"The reality is that the opposite has occurred and if we do privatise Royal Mail we will get a worse, not better service with cutbacks in deliveries and hiked prices, as the Netherlands' disastrous experience of postal privatisation proves."