Nicola Sturgeon has refused to back down on a second independence referendum, telling Boris Johnson that results in Scotland meant it was guaranteed to happen.

In a phone call with the Prime Minister, Scotland’s First Minister said it was a “matter of when – not if” another vote on whether to split the Union would take place following the election of a pro-independence majority in Holyrood.

Cabinet Office minister Michael Gove had used his Sunday broadcast interviews to signal that the UK Government was not prepared to sanction a follow-up to 2014’s referendum after the SNP failed to secure a majority at the Scottish parliament elections.

Mr Gove said the result, in which Ms Sturgeon secured a fourth successive term in power for the SNP but fell one seat short of gaining a 65-seat majority in the Edinburgh parliament, indicated that it was “not the case that the people of Scotland are agitating for a referendum”.

He instead urged the SNP to “concentrate on recovery” from the coronavirus pandemic.

But party leader Ms Sturgeon, in a discussion with the Prime Minister on Sunday, told him that the pro-independence outcome of the elections, with the Scottish Green Party also standing on a ticket of breaking from the rest of the UK, meant a second referendum had become inevitable.

A spokesman for Ms Sturgeon said: “The First Minister made clear that her immediate focus was on steering the country through Covid and into recovery, and that a newly elected Scottish government would work with the UK government as far as possible on that aim.

“The First Minister also reiterated her intention to ensure that the people of Scotland can choose our own future when the crisis is over, and made clear that the question of a referendum is now a matter of when – not if.”

The Prime Minister had looked to strike first by inviting Ms Sturgeon, along with the other devolved leaders, to a Union summit to discuss pulling together to propel a post-pandemic revival – an invitation the First Minister has accepted.

Downing Street said Mr Johnson finished his call with the SNP leader by “emphasising the importance of focusing on Covid recovery at this time”, as No 10 looks to kick talk of a referendum into the long grass.

Senior minister Mr Gove told the BBC’s The Andrew Marr Show that “a majority” of Scots “voted for parties that were opposed to a referendum” and that the public wanted “jobs and jabs” rather than “debate on the constitution”.

But Ms Sturgeon’s comments to Mr Johnson are a sign that the debate over the Union has only been further fuelled by the latest results north of the border.

Elsewhere, the Labour fallout over its poor showing in the elections has continued as leader Sir Keir Starmer embarks on a long-winded reshuffle of his shadow cabinet, which started with the sacking of his deputy Angela Rayner.

Party sources confirmed a reshuffle was under way on Sunday morning but there had been no announced change to his top team by the evening.

Sir Keir has faced stinging criticism after firing Ms Rayner from her role as party chairman and elections co-ordinator on Saturday, with Greater Manchester mayor Andy Burnham warning him it was “wrong”.

Jon Trickett, a former party campaign co-ordinator and prominent left-wing voice, said a leadership challenge should not be ruled out following the decision and the dismal results.

It comes after Labour received a battering in some parts of the country, losing control of a host of councils and suffering defeat at the hands of Boris Johnson’s Conservatives in the Hartlepool by-election, the first time the north-east town has elected a Tory MP since 1959.

But the internal recriminations followed on the back of an uptick in fortunes for Labour as more results came in over the weekend, with the party dominating in the mayoral elections, claiming 11 of the 14 posts contested in cities and metropolitan regions across England.

Labour secured shock victories in the West of England and Cambridgeshire and Peterborough while banking comfortable wins in Greater Manchester and Liverpool City Region, and holding onto London and Bristol.

On Sunday, Labour MP and former Coronation Street actor Tracy Brabin was elected the first West Yorkshire mayor.

The result sets up another potentially difficult Westminster by-election for the party in the wake of the Hartlepool defeat, with Ms Brabin’s Batley and Spen constituency considered to be in the so-called “red wall” of traditional Labour heartlands where the Tories have made gains in recent years.

Ms Brabin, who saw her majority slashed from almost 9,000 to 3,500 at the 2019 general election, told PA news agency she believed Batley and Spen “is a seat we’ll win” in a by-election.

“I think there is that understanding that a Labour MP, working with a Labour mayor and other Labour MPs across the region, we can really flourish,” she added.

Other parties were also celebrating significant victories on Sunday, with the Liberal Democrats taking control of St Albans council after gaining seats, while the Green Party more than doubled the number of councillors it has on Bristol City Council to become the joint biggest party with Labour.