He said: “My strong view is that decisions about people should be made as close to them as possible.
“I will wait for Gordon to finish his piece of work to answer your question in full because obviously there are huge issues bound up with any question of fiscal devolution.
“The general principle works, we can’t defend the status quo.
“I believe in the union and I think we need to make a stronger case for the union and I think we have been making a stronger case for the union.
“Until Gordon finishes his piece of work I am not saying anything about it one way or another.
“The most important thing is we make this powerful case for the union, and that’s why Anas [Sarwar] and I are working so closely together”.
A call for a second vote on Scottish independence to include devo-max on the ballot paper has previously been dismissed by several high-profile figures in the SNP.
Scottish Government minister Kevin Stewart branded the suggestion – from former SNP policy chief Chris Hanlon – “idiotic, foolish, nonsensical”, while MSP Gillian Martin rejected it as a “con”.
Starmer admitted his party had work to do in Scotland, specifically in convincing people Labour can win.
He said: “I need to persuade people in Scotland there is a real alternative to the Tory government in Westminster.
“I'm not surprised that in Scotland people feel disaffected by continuous Tory governments in Westminster particularly under Boris Johnson.
“We've got to prosecute the argument that this government under Boris Johnson is not fit for purpose.
"The next bit is to show that Labour is an alternative government in waiting and that's very much how I see 2022.
"It’s very important for voters in Scotland to have the hope we can have a Labour government in Westminster because that materially changes the lives of many people in Scotland.
"I want to focus on what brings us all together and what binds us together as a United Kingdom.
"We are all stronger together than we are apart and it's that basic argument that we need to get across.”
The Labour leader also joked the Prime Minister did not visit Scotland enough because of his popularity.
He explained: “He’s so unpopular in Scotland, and he knows it.
"I am up often, but I want to be up more often.”
The former head of the Crown Prosecution Service was also critical of both Boris Johnson and First Minister Nicola Sturgeon, accusing them of failing to focus on what matters to Scotland.
He said: “I think both Nicola Sturgeon and Boris Johnson have got their focus in the wrong place.
"Nicola Sturgeon is focused most of the time on the constitutional question, and not on the issues that matter so much to people in Scotland.
“So the focus is in the wrong place, and for the Prime Minister the problem is he’s focused on his own party, which he’s trying to hold together.
"He couldn’t have even got Plan B over the line in December if we hadn’t voted in the national interest.
“Where it goes next I think is a really important question whether you’re in Scotland, England, Wales or Northern Ireland.
"I firmly believe that mass testing, lateral testing is a big part of the way out of this to rapidly distinguish between those that do and don’t have it.
"That is the biggest Government failure at the moment, not having those lateral tests available.”
The Labour leader also urged action to help with the cost of living crisis, accusing the UK Government of “complacency”.
He explained: “Downing Street is costing working families because of the toxic combination of on the one hand inflation, obviously, which is predicted to go up six per cent, which is the highest since John Major was a government by the way, which tells you relatively how significant that is.
"Then you have got bills going up at the same time, whether that's fuel, food, or particularly energy.
“As those two elements are combining you've then got the Tories choosing this moment to introduce tax rises in April, in national insurance and across Scotland that is going to mean in real terms, £350 more that every working person will have to pay.
“Add to that the cut to universal credit, with 400,000 or so on it in Scotland so that’s £1000 that each of those families have lost.”
Sir Keir claimed the issue could be stopped now, and warned it would hit working families the hardest.
He said: “The link now between the complacency in Downing Street and the impact on working families is very direct.
“On energy bills we should cut VAT, it should be removed. Now, the VAT receipts over recent months have been far higher than the government expected and therefore, you could easily make that cut to energy bills and you could do it now, we called for it several months ago.
"The government's obviously squabbling about what to do, but it's not actually doing anything.
“The other thing is that we wouldn't introduce the national insurance taxes. We voted against them precisely because they were going to hit working families.
“There is an alternative out there but at the moment you've got people being hit both sides in this toxic combination in terms of the cost of living price.”
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