Nicola Sturgeon has spoken to Boris Johnson for the first time since he became prime minister.
The Scottish government said the first minister and Mr Johnson spoke on the telephone on Thursday evening.
Ms Sturgeon was said to have reiterated her strong opposition to a no-deal Brexit and again urged the prime minister to change course.
It is understood Mr Johnson, who has predicted a “golden age” for the UK, will visit Scotland on Monday.
The prime minister says the country will definitely leave the EU on 31 October and is confident an exit deal can be agreed before then.
There has been speculation that Mr Johnson will visit Scotland next week – but Downing Street has played down reports that he will hold a meeting of his cabinet in Glasgow on Monday.
Downing Street has confirmed that Mr Johnson told the first meeting of his cabinet on Thursday that he would be taking the title of Minister for the Union alongside that of prime minister.
A spokesman for the prime minister said: “It is a statement of his commitment to the strengthening of the Union and the value he places upon it.
The Scottish government said Ms Sturgeon had congratulated Mr Johnson on his appointment during their telephone conversation, before she set out her “strong opposition to a no-deal Brexit”.
Ms Sturgeon said the Scottish government would continue to make every possible preparation for no deal, but urged the prime minister to change course in order to avoid such an outcome.
She said immediately after Mr Johnson became prime minister that an independence referendum was now “more essential than ever”.
As well as Ms Sturgeon, the prime minister also spoke to Welsh First Minister Mark Drakeford, as well the leaders of the DUP and Sinn Fein in Northern Ireland, Arlene Foster and Michelle O’Neill respectively.
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The Scottish and Welsh first ministers sent Mr Johnson a joint letter shortly after his appointment to say it would be “unconscionable” for the UK to leave the European Union without a Brexit deal.
The prime minister’s spokesman said the discussions had been “positive”, with Mr Johnson insisting that he is going be the leader “for the whole of the United Kingdom”.
The spokesman added: “He wants to unite the country and unleash the productive power of every corner of England, Wales, Scotland and Northern Ireland.”
Mr Johnson is continuing to appoint more new junior ministers during his second full day as prime minister.
His appointments so far include Baroness Annabel Goldie, the former leader of the Scottish Conservatives, who becomes a minister at the Ministry of Defence.
He is also expected to unveil a ministerial team for the Scotland Office, who will work alongside the new Scottish Secretary Alister Jack.
Mr Jack took on the role after Mr Johnson sacked David Mundell on Wednesday in a move that is said to have left Scottish Conservative leader Ruth Davidson “livid”.
Ms Davidson had publicly urged the new prime minister to keep Mr Mundell in the job just days before he was sacked.
Mr Mundell backed Remain in the EU referendum and has been a vocal critic of Mr Johnson and the possibility of a no-deal Brexit in the past, while Mr Jack claimed on Thursday that leaving the EU without a deal would would not be “seriously damaging”.
Scottish Conservative MP Andrew Bowie told the BBC that Mr Johnson would be “very reckless” and making a “grave mistake” if he does not take Ms Davidson’s advice on Scotland in the future.
Mr Bowie served as the parliamentary private secretary to Theresa May during her time in Downing Street,