The drop in people’s living standards has “got nothing to do with Brexit”, the Prime Minister has insisted following warnings that the UK will slide into recession this year.

Rishi Sunak instead pinned the blame of rising costs on inflation and the war in Ukraine, as the SNP’s Westminster leader, Stephen Flynn, described the UK as a sinking “Brexit ship”.

Mr Flynn’s predecessor, Ian Blackford, meanwhile highlighted the International Monetary Fund’s warning of a looming recession in his first appearance at Prime Minister’s Questions since stepping down from his leadership role.

The IMF warned on Tuesday that the UK economy will contract by 0.6% in 2023 compared with the 0.3% growth it pencilled in last October.

In its latest World Economic Outlook update, the IMF increased its growth outlook for the global economy, but warned that Britain looks set to suffer more than most from soaring inflation and higher interest rates.

Whilst the Brexit ship sinks with the Prime Minister and the Leader of the Opposition at the helm, does he blame those Scots who want to jump aboard the independence lifeboat?

At Prime Minister’s Questions on Wednesday, Mr Flynn said: “Let’s be clear – taken together, 2022 and 2023 are expected to be the worst years for living standards since the 1930s and the economy is expected to perform worse than sanction-hit Russia.

“So, whilst the Brexit ship sinks with the Prime Minister and the Leader of the Opposition at the helm, does he blame those Scots who want to jump aboard the independence lifeboat?”

Mr Sunak replied: “The number one factor that is impacting people’s living standards (is) inflation caused by high energy prices as a result of a war in Ukraine.

“It’s got nothing to do with Brexit, and that’s why the Government is taking significant action, supporting every family with £900 this winter, but what I would say to him is, rather than obsess about constitutional arrangements, focus on delivering for the people of Scotland – that’s what we will do.”

The SNP Westminster leader had earlier asked Mr Sunak if he still believes the UK “can afford not to be in the EU”.

Mr Flynn said: “We’ve just marked the three-year anniversary of Brexit and we’ve learned – they’ll not be cheering in a moment – because we have learned three things: the UK’s trade deficit has grown, the economy is being hit to the tune of £100 billion each year, and of course we know that the UK’s economy is expected to be the worst-performing of all advanced nations.”

The Prime Minister responded: “If you actually look at it, since Brexit the UK has grown exactly the same as Germany, but, not only that, we are taking advantage of Brexit to deliver for the people across the UK.

“Whether it’s the fishing and farming communities of Scotland, whether it’s through the two new freeports that we’ve just announced… The difference between his party and ours is that we respect referendums.”

Mr Blackford was met with raucous applause from the Tory benches as he stood up to press Mr Sunak on the cost of living.

Conservative MP Alberto Costa could be overheard shouting “He’s back!”.

“Thank you, Mr Speaker, and thank you for that welcome,” he said to laughter.

The Ross, Skye and Lochaber MP added: “Ordinary people didn’t need to hear an IMF forecast to understand that the UK economy is the worst performer among the leading nations in the world. They live with it every day.

“People know their energy bills are through the roof, they know that 750,000 households face defaulting on their mortgages while house prices fall, and they know that food prices are rising at a record rate of 16.7% as of today.

“The Prime Minister is 100 days in office, his party 13 years in power. In all that time does the Prime Minister ever reflect that the only thing that the Tory Party have been good at is pushing people into poverty?”

“Aww,” replied Mr Sunak in a mocking tone, “it is wonderful to hear from him and lovely to see him in his place.”

The Prime Minister added: “He mentioned poverty. Poverty today? Lower than when the Conservatives first came into office. Inequality? Lower than when the Conservatives first came into office. And the number of people on low pay? The lowest on record.”