The Government is seeking to downplay a secret Whitehall dossier on the impact of a no-deal Brexit, with one minister dismissing it as "scaremongering" and Number 10 insisting it was leaked to influence discussions with the EU.
The leaked documents suggest the UK will be hit with a three-month "meltdown" at its ports, a hard Irish border and shortages of food and medicine as part of a series of "aftershocks" when it crashes out of the EU.
According to the documents, published in the Sunday Times, petrol import tariffs would "inadvertently" lead to the closure of two oil refineries, while protests across the UK could "require significant amounts of police resources" in a no-deal scenario.
A senior Whitehall source told paper: "This is not Project Fear - this is the most realistic assessment of what the public face with no deal. These are likely, basic, reasonable scenarios - not the worst case."
But when asked about the dossier, Business Minister Kwasi Kwarteng told Sky's Sophy Ridge on Sunday: "I think there is a lot of scaremongering around and a lot of people are playing into Project Fear and all the rest of it.
"We've got to prepare for no-deal. In fact the previous prime minister created DExEU and she said that the mandate of DExEU last year, last summer, was to prepare for no-deal...
"Now we've got a new Prime Minister who is very much focused on that and the scale and intensity of those preparations are increasing and we will be fully prepared to leave without a deal on October 31."
A No 10 source also claimed a former minister leaked the dossier to try to influence discussions with EU leaders.
Boris Johnson is heading to Berlin on Wednesday and Paris on Thursday in his first trip abroad as Prime Minister, when he will tell Angela Merkel and Emmanuel Macron that there must be a new Brexit deal.
"The document is from when ministers were blocking what needed to be done to get ready to leave and the funds were not available," they said.
"It has been deliberately leaked by a former minister in an attempt to influence discussions with the EU.
“Those obstructing preparation are no longer in Government, £2 billion of extra funding has already been made available and Whitehall has been stood up to actually do the work through the daily ministerial meetings.
"The entire posture of the Government has changed.”
Meanwhile, Michael Gove, the Cabinet minister responsible for no-deal planning, insisted Yellowhammer represented a "worst-case scenario".
He tweeted: "We don't normally comment on leaks - but a few facts - Yellowhammer is a worst case scenario - v significant steps have been taken in the last 3 weeks to accelerate Brexit planning - and Black Swan is not an HMG doc but a film about a ballet dancer..."
It came as Tory former cabinet ministers Iain Duncan Smith and Owen Paterson claimed the leak was an example of the "establishment" plot to "sow fear in people's minds".
In a joint statement, they said: "This Operation Yellowhammer leak is the version of what the contingency executive put together. We remember attending a briefing on privy council terms which they said was not worst case but reasonable worst case. Theresa May had asked for this to be done. It was obviously Project Fear dressed up.
"For example, on the delays at the port we asked if they had discussed their expectation with the port authorities of Calais/Pas du Nord who had already said that there would be no extra delays at Calais and they said, (after a great deal of shuffling of feet) 'no'.
"We asked why not and they said they had not been asked to do so. There were other areas where it was clear they had not been asked to get balance but instead dress up previous versions of other worst-case scenarios.
"The whole thing was an attempt to frighten us and didn't stand up to scrutiny. We have never seen officials look so uneasy under questioning.
"The fact that this document was 'found' in a Westminster pub tells you all you need to know about this continuing establishment plot to sow fear in people's minds. This is an abuse of the proper use of the Civil Service and must be stopped."