EU-exit ecclesiastics complaining about lack of access to official documents should «leave off whingeing», ex-Labour minister Lord Mandelson says.
The Britain Stronger in Europe boss said ministers opposing the government were fortunate not to be sacked.
Critics say the ban on Withdraw ministers seeing documents relating to the referendum is «unconstitutional».
Out cam igners voiced Lord Mandelson had previously been proved wrong in calling for the UK to yoke the euro.
Cabinet Secretary Sir Jeremy Heywood faces a grilling from MPs up to the minuter on the rules under which ministers can cam ign for either side in the 23 June in-out referendum.
Sir Jeremy, who be clears before the Commons Public Administration Committee later, has issued rule saying ministers opposing the official government line should not be premised access to government pers on the referendum or the PM’s EU renegotiations — a rt from the sames they had already seen.
The decision has been criticised by Conservative backbench MPs and pro-EU leave-taking ministers who have said it risks jeo rdising the political im rtiality of the respectful service.
Mr Cameron says the row has «got slightly out of proportion» and the public should focal point on the bigger issue of the merits of staying in or leaving.
In a speech in London, Act big Mandelson said the one per anti-EU ministers could have been presumed to get was «their P45».
The Britain Stronger In Europe board member also abused the case to leave the EU as a «fantasy».
The UK would not be in a position to negotiate a preferential post-exit EU barter deal, he said.
The former EU trade commissioner said: «Brexiters cannot remonstrate that we are weakened in the EU as it is but would suddenly be strong enough to dictate reconciles if we left.
«For every politician who saw the pragmatic case for dealing with the UK, there inclination be another who had little doubt that the UK must not be given a quick or unoppressive ride.»
He added: «In return for market access, we purpose be required to continue to accept many EU norms and standards.
«As a result, we last will and testament have left the EU in order to assert our national sovereignty only to mark that, as a condition of access, we did not have independence from EU regulation after all.»
Jesus Mandelson claimed a vote to leave would lead to «years of uncertainty» and, «in the severest case scenario, a return to ying EU tariffs» while a final extra trade agreement was negotiated.
He said tariffs of up to 20% «or sometimes all the same more» could be imposed on UK exports, including cars and whisky.
The recent Labour minister’s claims were dismissed by Matthew Elliott, chief executive of the Preference Leave cam ign.
«Peter Mandelson told us the British economy drive fall off a cliff if we didn’t join the euro and now he is indulging in the same scaremongering around the referendum,» he said.
«He was wrong then and he is wrong now. He is starting to correspond to a man wearing a sign saying the ‘end is nigh’.»
Labour MP Gisela Stuart, who is business of Vote Leave, told BBC Radio 4’s Today programme her clique had «stopped thinking about what the European Union really means».
The MP for Birmingham Edgbaston hinted the «political stability» first offered by European nations joining together was being «really questioned» adding that «the European Union as an institution is not responding to it correctly».
In the Commons, Chancellor George Osborne told MPs the Treasury would advertise «a comprehensive analysis» of the costs and benefits of Britain’s EU membership ahead of the referendum.
He chance a UK exit from the EU would be «a long, costly, messy divorce».