It forecast that the UK Department for Transport would have to boost its working ranks by more than 60% to deal with all the Brexit changes.
Colin Ellis, chief author of the report, said that while the United Kingdom and European Union "would likely take swift steps to limit short-term disruption", such a situation would still pose more significant credit challenges than a negotiated exit.
The DUP's Brexit spokesperson has accused Sinn Fein MEP Martina Anderson of "whinging" about government warnings over the possible need for global driving permits in the event of a no-deal Brexit.
"There's no deal without the whole deal", he wrote.
Competition law expert Alan Davis of Pinsent Masons, the law firm behind Out-Law.com, said "the unanswered question of what will happen to these ongoing merger and competition investigations could concern businesses especially given how close we are to the exit date".
The credit ratings agency said that the risk of a no-deal Brexit had "risen materially".
He also said there must be a "shift across the board in the EU's approach" on the issue of Northern Ireland: "They will have to meet us halfway. if they meet the ambition, the pragmatism we've shown through our White Paper proposals then I'm confident we can get a good deal for this country, but also for the European Union". The EU directive brought in in June 2017 which capped the prices mobile phone operators could charge each other will no longer apply to the United Kingdom after Brexit.
Finally, the United Kingdom government has warned that United Kingdom participation in the EU Space Surveillance and Tracking (EUSST) programme, kicked off in 2014, will also be at risk. However, it is right that in the event of a "no-deal" with the European Union, the government takes steps to make sure motorists know what is required when driving in European Union countries.
However, Carney also told the cabinet meeting that Britain could expect a 16 billion pound boost if there was a deal struck based on May's so-called Chequers proposals which involve a common rule book for goods trade with the bloc, the Financial Times reported. "It had been anticipated that a deal might have facilitated a more sensible outcome that involved the United Kingdom courts and competition authorities having "due regard" to CJEU rulings, but it is clear that a "no deal" scenario increases the risk of potential future divergence".