Osborne will be appearing at an event with former Labour Chancellor Alistair Darling, and is slated to unveil a string of tax rises to cover what he will describe as a £30bn ‘black hole’ in the UK’s finance if it is a ‘no’ vote for continued membership of the EU.

The tax hikes will include a 2p rise on the basic rate of income tax and a 3p addition to the higher rate, and raising IHT by 5p. There would also likely be a 5% rise on alcohol and fuel duties.

In addition, Osborne will say spending on pensions could be cut by £2bn and the Home Office, transport, and local government spending by 5% or £5.8bn, while the NHS budget could be reduced by £2.5bn, defence by £1.2bn, and education spending by £1.15bn, as well as cuts to policy force funding.

Later today Osborne will say: ‘Far from freeing up money to spend on public services as the Leave campaign would like you to believe, quitting the EU would mean less money. Billions less. It's a lose-lose situation for British families and we shouldn’t risk it.’

Darling will say that he is even more worried now than he was when Chancellor in 2008, at the height of the financial crisis.

‘Far from having more to spend on public services - the giant con trick at the heart of the Leave campaign - we'd have tens of billions of pounds less. As a former Chancellor, I have to tell you that would mean an emergency Budget where we would have to increase taxes and cut spending,’ he will say.

The Chancellor and former Chancellor have indicated they are basing their claims on research by the Institute for Fiscal Studies that warned leaving the EU could lead to an extra two years of austerity.

However, almost 60 Conservative MPs have written a letter to Osborne opposing the measures suggested for the emergency Budget, saying these would mean the party was breaking its election manifesto pledges, which included a commitment not to raises income tax rates during the lifetime of this Parliament.

In a statement the MPs said: ‘We find it incredible that the Chancellor could seriously be threatening to renege on so many manifesto pledges.

"It is absurd to say that if people vote to take back control from the EU that he would want to punish them in this way...

‘If the Chancellor is serious then we cannot possibly allow this to go ahead. It would be unnecessary, wrong and a rejection of the platform on which we all stood. If he were to proceed with these proposals, the Chancellor's position would become untenable.’

Asked about the letter, Osborne said: ‘The Conservative Government would do what was needed to deal with the chaos in our economy.’

The UK votes on whether to remain in the EU or to leave on 23 June.