A £3 billion green package with grants for homeowners and public buildings to improve energy efficiency will be unveiled by Rishi Sunak as part of his coronavirus economic strategy.

The Chancellor will unveil a raft of measures in his Commons statement on Wednesday, including £2 billion for households to insulate their homes and make them more energy efficient, according to The Sun.

Hospitals, schools and other public buildings are set to receive £1 billion for measures such as insulation, efficiency and green heating technology.

The funding aims to help the UK “build back greener” and meet its legally binding target to cut greenhouse gas emissions to net zero by 2050, but campaigners say it “doesn’t measure up to the economic and environmental crises”.

Mr Sunak is meanwhile being urged to inject more than £200 billion into the economy to “secure” Britain’s economic recovery from the virus, as the International Monetary Fund warns the UK’s gross domestic product (GDP) could drop by 10.2%.

The Resolution Foundation think tank has called on the Chancellor to loosen the purse strings and announce a fiscal package worth 10% of GDP.

It recommends a stimulus package include a £17 billion per year job support package which would see the furlough scheme extended and job guarantees for young people.

James Smith, research director at the think tank, said: “The measures the Chancellor announces in his mini-Budget tomorrow need to be big enough to reflect the size of the crisis we face, targeted at the sectors that need the most support, and flexible enough to cope with the uncertainties that lie ahead.

“A £200 billion fiscal stimulus should therefore focus on protecting jobs and supporting spending in hard-hit sectors of the economy, and reflect the fact that low-income households have found it far hardest to cope.”

It comes as a number of pubs which reopened their doors for the first time on Saturday announced they have had to close again due to people testing positive for coronavirus.

Bars in England welcomed drinkers at the weekend after a lengthy lockdown which saw the hospitality sector shut since March, but three establishments have since alerted their patrons that they have had to close again just days later due to cases of Covid-19.

The closures will cause concern in the sector, which has been acutely affected by the crisis.

Boris Johnson on Monday urged people not to “stuff this up” after drinkers flocked to popular areas, including London’s Soho, over the weekend, prompting fears over the lack of social distancing.

The Prime Minister said he was not shocked by some of the scenes over the weekend because “I understand what human nature is” but said: “We cannot be complacent, we really can’t afford to stuff this up, to blow it now.”

Meanwhile, Mr Johnson was criticised by care providers after he said that “too many” care homes did not properly follow procedures during the coronavirus pandemic.

The PM’s comments came after he was asked what he made of Sir Simon Stevens’s desire to see plans to adequately fund the adult social care sector within a year.

Mr Johnson said: “One of the things the crisis has shown is we need to think about how we organise our social care package better and how we make sure we look after people better who are in social care.

“We discovered too many care homes didn’t really follow the procedures in the way that they could have but we’re learning lessons the whole time.

“Most important is to fund them properly… but we will also be looking at ways to make sure the care sector long term is properly organised and supported.”

But care providers said the basis for the PM’s comments was unclear, while the National Care Forum (NCF) urged him to start “turning the dial up on reform and down on blame”.