Boris Johnson has set the UK on an "almost inevitable path to a no-deal Brexit", Scottish First Minister Nicola Sturgeon has claimed.
Ms Sturgeon's comment came after talks with the new PM at her official Bute House residence in Edinburgh.
She said it was clear to her that the UK government was on a "dangerous" path to a "catastrophic" exit from the EU.
Mr Johnson said he was "very confident" that with "goodwill on both sides" a new agreement Brexit could be drawn up.
He said the existing withdrawal agreement drawn up with European leaders was "dead", but added that he would "hold out the hand" and "go the extra thousand miles" in pursuit of a new deal.
In what Ms Sturgeon described as a "very lively exchange", she revealed the prime minister reiterated his opposition to Scottish independence and the two sides had a "robust exchange" about the first minister's suggestion for the two leaders to hold a TV debate on the future of the Union.
Mr Johnson has pledged to take the UK out of the EU by October 31, with or without a deal.
During a visit to the Faslane naval base near Glasgow on Monday morning, the prime minister said his "assumption is that we can get a new deal", but said it was "responsible for any government to prepare for no deal if we absolutely have to".
He then headed to Edinburgh for talks with Ms Sturgeon, who warned that a "catastrophic" no-deal departure would cost 100,000 jobs in Scotland and "plunge the economy into recession".
Following the meeting at Bute House, the SNP leader said that "behind all the bluff and bluster, this government and the path it is pursuing are dangerous".
She said: "It became clear to me that this government, the new prime minister, has set the UK on an almost inevitable path to a no-deal Brexit.
"The position it has taken makes it very difficult to see how any deal can be struck with the EU and I think that would be catastrophic for Scotland and indeed for the whole of the UK.
"I made abundantly clear to Boris Johnson my opposition to Brexit and to no-deal. I also made it clear to him that the people of Scotland should be able to chart their own course and choose their own future, not have that future imposed upon them."
'No clarity at all'
The first minister said Mr Johnson had not convinced her that he had a plan to break the current deadlock, with MPs at Westminster unable to agree on a deal which would be acceptable to the EU side.
Ms Sturgeon said: "He says he wants to get a deal, but what is not clear to me is how he intends to get from the very hard-line, fixed position that he's taken to a position where a deal is possible, if the EU also sticks to the very consistent position it has taken.
"That is where there is no clarity at all. That makes me think that whatever Boris Johnson is saying about his preference being to strike a deal, in reality he is pursuing a no-deal Brexit, because that is the logic of the hard line position he is taking."
On the issue of independence, the first minister said the two leaders had a "very lively exchange of views about independence".
She added: "I made clear my government's intentions to pass the framework bill to allow a referendum to take place next year.
"He made the case that he was for the Union, and didn't think Scotland should have the right to choose. And we had a to-ing and fro-ing on the pros and cons of independence."
Following the meeting, a Downing Street spokesman said Mr Johnson had stressed that "while the government's preference is to negotiate a new deal which abolishes the anti-democratic backstop, the UK will be leaving the EU on October 31 come what may".
He added that Mr Johnson "set out the scale of work under way" and offered to set up a summit with the heads of the devolved governments "soon".
He said the prime minister wanted to "work with the devolved administrations to make sure all corners of the UK are ready to enjoy a bright future outside of the EU".
Mr Johnson also held talks with Scottish Conservative leader Ruth Davidson, who has said she could not support a no-deal Brexit.
She said she backed Mr Johnson's "preference" of leaving the EU with a deal "wholeheartedly", and said it was the SNP who had been "utterly hypocritical" by voting down former Prime Minister Theresa May's Brexit deal on three occasions.
She said: "Rather than complain from the sidelines, it's time the first minister worked with colleagues across the UK, and supported a deal that delivers on the referendum result, gives clarity to Scottish business, delivers for the Scottish fishing industry, and works for us all."
Ms Davidson did not support Mr Johnson in the Conservative leadership, and reportedly clashed with him over his decision to sack David Mundell as Scottish Secretary.
However, she said the prime minister was "in full listening mode" during his visit to Scotland, and said he had shown he was "engaged" and "committed" to the UK union.
Mr Johnson meanwhile said he was Ms Davidson's "number one fan", and stressed that the two have much in common politically.
He said: "It's she who's taking the fight to the Scottish Nationalists, those would destroy the union. She's been fantastically successful and I admire her brand of conservativism very much - she and I share a huge range of political beliefs and our core philosophy is the same.
"I also think she's right that we should be going for a deal, not no deal. That's where we should be trying to end up, but it's the responsibility of the government to make sure we are prepared for every eventuality. And if our partners won't move and won't take out the backstop or change the withdrawal agreement or compromise at all, then of course we've got to get ready for no deal.
"I think it's absolutely vital that a responsible government of the UK has got to be ready to walk away from the table because otherwise I don't think we'll have credibility in the talks."
Meanwhile, a former chairman of the Scottish Conservatives believes it is "inevitable" that the party will split away from the UK Conservatives.
Peter Duncan, who was a Scottish Tory MP between 2001 and 2005, told BBC Scotland's The Nine that the direction of travel meant the parties would ultimately separate.
Mr Duncan refused to put a timescale on any split, but he added that Brexit and Boris Johnson as prime minister could speed up the process of the Scottish Conservatives going their own way.