The risk of Britain stumbling into a "disorderly" no-deal Brexit is now "alarmingly high", Bank of England governor Mark Carney has warned.
He told Sky News that although "real progress" had been made preparing for leaving without a deal, it would still mean "lots of things to worry about".
And it was "absolute nonsense" a no deal could be easily managed, he said.
BBC economics correspondent Dharshini David said critics will see the remarks as another political intervention.
Last August the governor said the risk of the UK leaving without a deal "felt uncomfortably high", and his latest comments appear to ratchet up the language.
He said that since his remarks last year the situation had not got any better. "Unfortunately I think it proved accurate. It's alarmingly high now."
Britain's default option is that it leaves the EU on 12 April. On Wednesday, Prime Minister Theresa May held talks with Labour leader Jeremy Corbyn to try to find a way out of the current deadlock. But that drew criticism from some Conservative Tory MPs.
Mr Carney told Sky News: "We're in a situation where the expressed will of Parliament is for some form of deal, so to put it in the double negative - Parliament is against no deal, the government, as expressed by the prime minister, is against no deal, the European Union is against no deal, and yet it is a possibility, it is the default option.
"So no deal would happen by accident, it would happen suddenly, there would be no transition - it is an accidental disorderly Brexit."
He took aim at the idea promoted by several Brexiteers - and included in the Malthouse Compromise plan - which assumes that Article 24 of the General Agreement on Tariffs and Trade would allow free trade to continue with the EU while negotiations are in progress.
"Forget the fiction, it's absolute nonsense. It needs to be called out," he said.
"I might point out that they want to become better acquainted with the Secretary of State for Trade [Liam Fox] who in Parliament has made the point that it cannot apply unless both parties agree, and unless you're moving towards a - guess what - a customs union."
Mr Carney insisted that London's financial centre was ready to cope with the impact of a no-deal Brexit.
"There are a lot of things to worry about in the event of a no-deal Brexit, but the financial sector is not one of them," he said.