Nicola Sturgeon has underlined her plan to hold a second referendum when she spoke with Rishi Sunak for the first time since he became Prime Minister earlier today.

The First Minister congratulated Mr Sunak on his appointment, reaffirmed her wish for a "constructive working relationship" and for their relationship to be built on "mutual respect".

She also called on the Prime Minister not to pursue a programme of austerity as his Chancellor Jeremy Hunt prepares to deliver a new budget statement.

Experts have warned of the prospect of considerable cuts to public services and tax rises. 

“The First Minister and the Prime Minister had a brief, introductory call this evening. The First Minister congratulated the Prime Minister on his appointment and wished him well," a Scottish Government spokesman said following this evening's phone call.

“She expressed her hope that political differences notwithstanding, they would build a constructive working relationship. She made clear that the Scottish Government would do everything possible to establish such a constructive relationship but stressed that this must be built on mutual respect.

“The First Minister also expressed the strong view that the UK Government should address the pressure and pain being felt by people and businesses as a result of inflation and other economic pressures, and should not exacerbate that with a further wave of austerity.

“She welcomed the Prime Minister’s assurance of engagement with the devolved Governments ahead of the Chancellor’s forthcoming budget statement."

She added: "Finally, the First Minister made clear her intention to honour the mandate the Scottish Government received from the people of Scotland at the last election.”

The phone call was made less than 12 hours after Mr Sunak became Prime Minister this morning.

During a busy evening he also spoke to the President of Ukraine, Volodymyr Zelenskyy, to underline the United Kingdom’s steadfast support for Ukraine and to US President Joe Biden.

His prompt call with the First Minister marks a distinct change from the attitude of Mr Sunak's predecessor Liz Truss who did not call Ms Sturgeon at all during her 49 days in Number Ten or have any meetings with her.

During the Conservative leadership campaign in the summer Ms Truss described Ms Sturgeon as 'an attention seeker' who was best ignored.

It is customary for a new Prime Minister to speak early with the leaders of the devolved governments for Scotland, Wales and Northern Ireland. 

But ahead of the SNP conference earlier this month, Ms Sturgeon told ITV: "I have not yet had a phone call with her [Truss], which is unprecedented."

She also told Chris Mason, the BBC’s political editor, this month that she had not had a conversation with Ms Truss since she was appointed Prime Minister on September 6, other than “an exchange or two” at events after the death of the Queen.

“It’s quite absurd in many ways. When I became First Minister, David Cameron was Prime Minister and I think we spoke on the phone the first night I became first minister,” she said.

“I spoke on the phone to Theresa May within a day or two of her becoming Prime Minister, same with Boris Johnson actually.

“I have deep political differences with all of these politicians, but we have a duty to work together constructively.”

One of Mr Sunak's most prominent supporters in Scotland, the MP Andrew Bowie, has said the new Prime Minister will attempt to build a relationship of “respect” between the UK and Scottish Governments after years of animosity and rancour.

Mr Bowie, the Conservative MP for West Aberdeenshire and Kincardine, suggested that Mr Sunak will provide a significant shift in attitude from Downing Street towards Bute House.

"A priority for Rishi is firstly to re-establish an element of respect between the UK government and Scottish Government,” he told The Times last night.

“For quite a while there has been a feeling that the UK government was overruling or overriding the Scottish Government. That is unsustainable. We need to govern in the best interests of the Scottish people and to do that we need to be seen as working together.”

The scheduled phone call by Mr Sunak to the First Minister suggests a move back towards a more collaborative approach advised by Michael Gove when he had ministerial responsibility for the Union, and by Lord McInnes of Kilwinning when he was Boris Johnson’s Union adviser and Alister Jack, the Scottish Secretary.

Meanwhile, Mr Sunak - the UK's third Prime Minister since September - announced his new cabinet shortly after being appointed as Prime Minister by King Charles this morning.

This included Jeremy Hunt remaining as Chancellor, James Cleverly as foreign secretary, Ben Wallace as defence secretary and Suella Braverman returning as home secretary.

Mr Jack was reappointed to the role of Scottish Secretary this evening.

In a statement, he said: “I am very pleased to have been reappointed as Scottish Secretary.

“We are facing very significant challenges both at home and abroad, and there is much to be done.

“We need to bring stability to our economy and our public finances, deliver long term prosperity for everyone in our country, and continue to sustain and strengthen the Union.

“We will build on our track record of supporting families and businesses in Scotland, and investing millions directly into Scottish communities.

“I very much look forward to working with the Prime Minister to deliver for all parts of the United Kingdom.”

Ahead of the Conservative leadership hustings in Perth in August, Mr Sunak accused Ms Truss of being "dangerously complacent" about Ms Sturgeon and the Union following her remarks about ignoring the First Minister.

The former Chancellor said that "we can't just bury our heads in the sand and pretend" the SNP does not exist.

He said he wanted to "take Nicola Sturgeon on" and warned the SNP poses "an existential threat" to the Union.

He ruled out allowing another vote pn independence for as long as he was Prime Minister and said Ms Sturgeon would face a public backlash over her plan to use the next general election as a "de facto" independence referendum.