Labour has dismissed the need for the Government to spend more than £9 million of taxpayers' cash on pro-EU leaflets.
Shadow chancellor John McDonnell insisted there is enough campaign literature being provided by the in and out camps, ensuring the Government has no need to produce any extra.
The senior Labour MP also warned "Project Fear" is being carried out by all sides of the debate as he stressed the need for voters to be given "straightforward factual information".
Labour is firmly behind Britain staying in the EU with the party's deputy leader Tom Watson telling an event in Coventry that 213 of the Opposition's 232 MPs support a Remain vote.
But Mr McDonnell's remarks highlight concerns across the campaigns over the leaflet scheme.
Ministers face being forced to justify in Parliament the decision to spend cash on the pamphlets after a petition opposing the idea secured the required 100,000 signatures.
The move to send one to every household in the country setting out the case for voting to remain in the EU in June's referendum provoked a blistering row between Remain and Leave supporters.
Justice Secretary Michael Gove attacked the idea of taxpayers funding "one-sided propaganda" rather than the NHS after Prime Minister David Cameron insisted it was "money well spent".
Speaking during a visit to north London, Mr McDonnell said the public needs a factual and reasoned debate.
He said: "To be frank, I don't think there's a need for leaflets from Government.
"I'm also concerned about Project Fear from all sides of this debate. All people want is straightforward factual information which they can make up their minds on and I think we need to ensure the level of debate is about factual information, reasoned debate.
"I don't think there's a need for Government leaflets, there's enough out there from individual campaigns."
The petition, submitted by Get Britain Out director Jayne Adye, soared past the 100,000 mark on Thursday meaning it has to be considered for debate in Parliament.
It says: "We, the petitioners, demand the Government STOPS spending our money on biased campaigning to keep Britain inside the European Union.
"The Great British Public have waited since 1975 for a vote on our relationship with Brussels. No taxpayers' money should be spent on campaign literature to keep Britain inside the EU."
Downing Street said the leaflets were a response to polling which showed 85% of the public wanted more information from the Government to help them make an informed choice on June 23.
The Electoral Commission watchdog had campaigned for a ban on such Government activity during the formal "regulated period" of the campaign, which begins on April 15.
The leaflet is due to start hitting doormats in England next week, but not until after the May 5 elections in the rest of the UK.
Although ministers backed down from a significant lifting of the pre-vote "purdah" period during which government activity is restricted, legal restrictions still apply only for the final 28 days.
Mr Watson, in a speech to launch a document entitled "The Leave Campaign's Hidden Agenda", hit out at Tory, Ukip and Brexit supporters who he claimed "reserve a special sort of disdain" for rules which make the workplace safer.
He said: "These are the rights that the Tory and Ukip 'out' crowd - (Chris) Grayling, Iain Duncan Smith, Michael Gove, Nigel Farage, Boris Johnson - want to take away from British working people.
"That's the true agenda of the five Tory figures who are beating the anti-EU drum most loudly.
"If they were a pop band, it's unlikely I know, they'd be called Wrong Direction - because that's the direction in which they want to take the UK."