Every household will suffer a £575 annual blow due to the slump in the economic growth forecast, even before the impact of the coronavirus is factored in, a respected think-tank has warned.

The Resolution Foundation said the GDP markdown from the Office for Budget Responsibility (OBR) financial watchdog was both "incredibly grim and yet still unbelievably optimistic".

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Chancellor Rishi Sunak used his Budget to inject £30 billion in supporting the economy and softening the blow of the Covid-19 sickness ahead of the Government's expected ramping up of measures on Thursday.

The OBR warned that a "recession this year is quite possible" if the virus causes "widespread economic disruption", and predicted falling growth even before the coronavirus impact is reflected.

In its overnight assessment, the Resolution Foundation living standards think-tank delivered a stark warning over the OBR assessment, warning of "more difficult budgets ahead" for the Chancellor.

Chief executive Torsten Bell said: "The OBR managed to deliver an incredibly grim, and yet still unbelievably optimistic, pre-pandemic markdown to the UK's economic outlook - dealing a £600 a year hit to every household in Britain.

"In reality, once we take the economic impact of coronavirus into account, this is the weakest official growth outlook on record.

"And having finally returned to peak pay this year, real wage growth is set to weaken every year of the forecast period."

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Before the impact of coronavirus is seen, growth was expected to fall to 1.1% in 2020, down from 1.2% last year and dramatically lower than the OBR's previous estimate of 1.4%.

The Resolution Foundation said the forecast leaves the economy £8.6 billion smaller in 2020 than anticipated last year, representing a £310 slump per household, with this drop rising to £575 in 2023.

The think-tank also warned of "big income shocks" for self-isolating workers with two million low-paid employees still lacking Statutory Sick Pay entitlement.

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Later on Thursday, the influential Institute for Fiscal Studies think tank is to give its full verdict on the Budget.

Boris Johnson was also expected to announce after a Cobra meeting that the UK would move into the next phase of efforts to combat the coronavirus by seeking to delay the spread.

The Prime Minister's plans may include encouraging employees to work from home, shutting schools and advising elderly people to stay away from social contact.