Boris Johnson will today deliver a major speech on the government's imminent economic stimulus package, promising to engineer a Roosevelt-style 'New Deal' that will see the UK "build build build" in pursuit of a rapid economic recovery from the coronavirus crisis.

In a speech in the Midlands later today, the Prime Minister is expected to say the government's goal is to "build back better, build back greener, build back faster, and to do that at the pace that this moment requires".

But the trailed speech faced immediate criticism from green groups and some economists, who said there appeared to be few new environmental measures and also questioned whether the anticipated announcement of £5bn of accelerated infrastructure funding was worthy of the 'New Deal' tag given the US President's Depression era stimulus package was orders of magnitude larger.

Johnson is expected to use the speech to reiterate his promise to avoid an austerity-style response to the current economic crisis and instead forge ahead with his plans to "level up" the UK's regions.

He will argue that the coronavirus crisis has provided an opportunity "to build the homes, to fix the NHS, to tackle the skills crisis, to mend the indefensible gap in opportunity and productivity and connectivity between the regions of the UK".

"Too many parts of this country have felt left behind, neglected, unloved, as though someone had taken a strategic decision that their fate did not matter as much as the metropolis," he will add. "And so I want you to know that this government not only has a vision to change this country for the better, we have a mission to unite and level up."

Specifically, he is expected to announce a £5bn investment drive, much of which will be funded by pulling forward existing plans.

It is set to include £1.5bn for hospital upgrades, £100m for new road network projects, £1bn for a new schools building projects, over £120m for prisons maintenance and upgrades, and £900m for 'shovel ready' local infrastructure projects that can be delivered this year and next.

On the environmental front, Johnson is expected to announce up to £1m each for areas eligible for the government's Towns Fund to enhance parks, high streets, and transport links, and he is set to re-affirm plans to plant trees on more than 75,000 acres a year by 2025. The goal is backed by £40m for local conservation projects that is expected to create 3,000 jobs and safeguard a further 2,000.

Separately, the government today confirmed that companies that applied to the Renewable Heat Incentive (RHI) tariff guarantee scheme before June 29 will have an extra 14 months to get their low-carbon heat generators up and running. The government said the move would bring vital clarity to companies in danger of missing the start-dates for their projects, protect investment in the renewable heat industry, and help give certainty to thousands of people working in specialised UK supply chains.

However, while welcoming the confirmation of funding for promised tree-planting programmes and the boost for renewable heat technologies, green groups were left largely underwhelmed by the trailed announcements.

Critics noted that the reported wave of new projects did not include the government's manifesto pledge to invest £9.2bn in improving building energy efficiency, while other big ticket green infrastructure projects were notable by their absence. Moreover, the size of the £5bn plan set to be announced today was contrasted unfavourably with the German government's recently confirmed €40bn green recovery plan.

Government sources countered that Chancellor Rishi Sunak is set to deliver a wider economic update to Parliament next week, while plans are also proceeding to deliver a wide-range of new green programmes throughout the course of the year. New funding and policies for energy efficiency, R&D, carbon capture and storage, electric vehicles, hydrogen and other areas are all said to be in the pipeline, alongside a new National Infrastructure Strategy, Enegry White Paper, and formal national climate action plan that is to be submitted to the UN ahead of the COP26 Climate Summit in Glasgow.

However, with reports suggesting the Prime Minister's chief advisor, Dominic Cummings, is keen to water down the promised energy efficiency package and the long-awaited National Infrastructure Strategy now not expected until the autumn, environmental groups are growing increasingly concerned about the pace at which the government's touted 'green recovery' plans are proceeding.

"Boris Johnson's speech should have fired the starting gun on a healthier, more resilient future for the UK," said Shaun Spiers, executive director of think tank Green Alliance. "Unfortunately, the PM seems to have got off to false start.

"This statement today is about putting shovels in the ground, but there is no point in that in the long term if it digs the UK deeper into trouble. Whether it's 'build, build, build' or 'jobs, jobs, jobs', thousands of constituents around the country are today lobbying their MPs to say they want a truly green recovery.

"Let's hope the Chancellor is listening and ups the government's game next week - putting people, climate and nature front and centre of the government's recovery strategy."

The Climate Coalition group of green NGOs is today staging a virtual lobby of Parliament, which will see thousands of constituents from across the UK engage in online meetings with over 100 MPs to urge them to back an ambitious green recovery programme.

However, Ed Matthew of the Climate Coalition offered a damning assessment of the Prime Minister's heavily-trailed speech. "The only thing Rooseveltian about this plan is that it belongs in the fossil fuel age," he said. "There is very little announced today which will do anything to accelerate the transition to a zero carbon economy. The prime minister has to back up his rhetoric on a green recovery with action to prioritise green investment. Future generations will not forgive a government that fails to use this opportunity to build a safer climate for us all."

Meanwhile, business groups are also stepping up calls for Chancellor to deliver a wide-ranging green stimulus package.

The Association for Decentralised Energy (ADE) today welcomed the Prime Minister's calls for an "infrastructure revolution". But warned "it is not enough to just 'build, build, build' to really put the country into the green economic recovery it urgently needs".

"By 2050, UK families will still be living in 80 per cent of the housing stock that is standing today- already old and in need of refurbishment and retrofitting in order to meet net zero targets," the group said. "Unlike other stimulus options, the jobs created by a national buildings renovation programme would be distributed across the entire country, with opportunity positively correlated to areas most in need of stimulus."

Bruce Davies, co-founder and managing director at green finance specialist Abundance Investment, similarly urged the government to accelerate its green recovery plans.

"Investment into shovel ready green projects is proven, by numerous academic studies from the likes of LSE and Oxford, to be the most effective way to both 'build, build, build' and create 'jobs, jobs, jobs'," he said. "We need to make sure that we don't waste time and miss the opportunity to make real progress on the pressing need to tackle the climate emergency. Funding the green recovery is proven as the most effective means of economic stimulus and so it is disappointing to see that lack of ambition in the package announced so far. We have to hope the government listens to the people and produces a budget which really does build back greener."

However, Labour's Shadow Chancellor Anneliese Dodds warned the government's decision not to deliver a full Budget until the autumn risks jeopardising any recovery.

"Our country is suffering the worst economic hit of all industrialised nations, but instead of the back-to-work budget our country needs focusing on one thing - jobs, jobs, jobs - the chancellor will only be providing an 'update' on the economy," she said, adding that the government should "abandon their 'one-size-fits-all' approach to the economic support schemes" and pursue a "concrete action and a laser-like focus [on] preventing further job losses and supporting future employment".