Labour’s shadow chancellor has pledged a £70 billion boost for the Scottish economy, as he insisted the party was “coming for power”.

John McDonnell outlined how a future Labour government would increase spending north of the border, pledging money for public services and for infrastructure investment, along with the possibility of speed rail up to Scotland.

He revealed details of the cash as he closed the Scottish Labour conference in Dundee.

He said there could be an extra £3 billion a year in Barnett consequentials – cash that comes to Scotland as a result of spending decisions taken by the UK – amounting to £30 billion over 10 years.

He also said Labour’s £250 billion National Transformation fund would see £20 billion spent in Scotland over a decade, that could help “rebuild our crumbling infrastructure and deliver key investments such as extending HS2 to Scotland”.

A UK National Investment Bank could provide another £20 billion in Scotland over 10 years, helping small and medium businesses.

Mr McDonnell said: “Let’s do the sums. Taken together, our commitments over a decade could mean an additional £70 billion for the Scottish economy.”

And he compared the spending from Labour’s planned UK Investment bank with the SNP’s “measly £340 million” of initial capital for the “so-called Scottish Investment Bank”.

He told the nationalists: “If you are going to steal our ideas, for goodness’ sake do it with a bit of style.”

The shadow chancellor used his speech to condemn the austerity being imposed on people by both the UK Conservative Government and the SNP administration in Edinburgh.

Under the nationalists he claimed Scotland’s economy was “stagnating”, telling party activists: “There has been nothing done in the last 10 years to grow the economy, to tackle the blight of poverty that is scarring Scotland.

“Both north and south lives are being destroyed and millions have been left in despair, and it is thanks to the failed economic dogma of neoliberalism and austerity.

“Austerity is a political choice, it’s not an economic necessity. And the Tories and the SNP, they chose austerity.

“We choose the socialism, we choose the alternative.”

With Scottish Labour having elected left-wing MSP Richard Leonard as its new leader in November, Mr McDonnell also insisted the party was heading back to power in both Westminster and Holyrood.

He told the conference: “Let the message ring out from this conference and every Labour Party meeting. We have had enough, we’re not taking any more.

“We’re coming for power and to power and we will seize it in Scotland as we will in the rest of the UK.”

The results in the 2017 general election, where Scottish Labour increased its tally of MPs from one to seven, and came second to the SNP in several other areas, had “cheered his heart”, he said.

Mr McDonnell told the conference: “You’ve not just won seats now, you’ve made us close to winning in many more Scottish seats that are now considered marginals.

“And its these seats that will hold the key to victory at the next election. So Scotland will decide whether we have a Labour or Tory government. You will be the people who will make the difference.”