A leaflet will be sent to every home in the country before the June 23 referendum and a new website has been launched which will be advertised on social media.
Downing Street insisted independent polling showed people wanted information from the Government about the issue of EU membership.
But the use of £9.3m of taxpayers’ cash to back the ‘remain’ argument has prompted outrage from ‘leave’ campaigners.
Environment Secretary Liz Truss said: “This referendum will be a huge decision for our country, perhaps the biggest we will make in our lifetimes and it is crucial that the public have clear and accessible information.”
The leaflets will be sent out in April and May before a 28-day limit on Government publications comes into force ahead of the referendum.
Conservative backbenchers and Labour MPs united last year to defeat David Cameron over plans to suspend the normal rules covering Government announcements and spending before elections.
The official ‘remain’ and ‘leave’ campaigns will be given money by the electoral commission to send their own leaflets to every household.
Downing Street said the latest publication followed the precedent set by similar leaflets ahead of the Scottish independent referendum and the last EU referendum.
But opponents said it was a waste of public money that breached ministers’ assurances that the Government would not seek to play a significant role in the campaign and unfairly skewed the debate.
Ukip leader Nigel Farage said the document was “jammed full of lies and inaccuracies” and was legally questionable and morally wrong and London Mayor Boris Johnson branded it “very biased and hysterical”.
The leaflet is costing £458,500 to create, with £5,947,436 being spent printing and delivering it to over 27 million homes across the UK in two waves - to the fury of “leave” campaigners.
Another £2,894,064 will go on producing the website and promoting it via social media and other online platforms - a total cost of around 34p per household.
The leaflet, titled “Why the Government believes that voting to remain in the European Union is the best decision for the UK”, will start to arrive through letterboxes in England next week - before “purdah” restrictions come into force ahead of May’s local elections - and in Scotland, Wales and Northern Ireland from the week after the May 5 elections.
The leaflet tells voters that leaving the EU would “reduce investment and cost jobs”, could push up food prices and damage living standards and that there would be “no guarantees” that flights to European destinations would rise, mobile phone roaming charges go up and access to free or cheaper healthcare on holiday come to an end.
The cost of the promotional push was greater than the £7 million each the formal “leave” and “remain” camps will be allowed to spend by law in total during the last 10 weeks of the campaign, Vote Leave complained.
Mr Johnson - one of several leading Tories to have broken ranks to back Brexit - said it was “crazy to use quite so much taxpayers’ money on stuff that is basically intended to scare people and to stampede people in one direction”.
“What we want is a proper, informed debate and if you are going to use taxpayers’ money you should allow people to put the other side of the case as well”.
Mr Farage said: “This Government scam confirms my view that this referendum will be defined by the battle of the people versus the political class.
“Furthermore, the document is jammed full of lies and inaccuracies including the claim that we currently control our borders. We don’t. It is outrageous to suggest otherwise.”
Tory MP Peter Bone, co-founder of the Grassroots Out campaign, said it was “immoral, undemocratic and against what the Government has promised”.
And Liz Bilney, chief executive of the Leave.EU campaign, said it was “putting the legitimacy of the final result at great risk”.