Robert Chote, the chairman of the Office for Budget Responsibility, said he had not endorsed either side in the referendum.
The head of George Osborne’s independent budget forecaster has insisted his organisation has reached no view on Brexit.
The Chancellor infuriated the many Conservative MPs supporting the campaign to get Britain out of Europe when he used Office for Budget Responsibility forecasts in support of EU membership.
But Robert Chote, the OBR’s director, told the BBC: ‘Parliament has told us to produce our forecasts on the basis of current government policy and not to look at any alternatives.
‘Current government policy is to stay in the EU so our forecasts are done on that basis. So we haven’t done any projections on what difference it would make if we left.’
He added: ‘But what we have also pointed out is that if you look at things City economists and other economists are saying, if there was to be a vote to leave then people expect a period of uncertainty while a new relationship with the EU is negotiated and that could have implications for consumers and business confidence and financial markets.
‘So we cited what other people have been saying [on] that but we’ve made no explicit judgements.’
He later told the Daily Telegraph: ‘We are reporting on the weight of views that are expressed outside, we are not saying that we endorse any quantitative estimate and we are very definitely not taking a view on the long-term consequences of In versus Out.’
He added: ‘We are not attempting to quantify what the impact of the No vote will be – leaving aside the longer-term issues.
‘We just thought it was sensible to recognise the fact that this is a risk – lots of other people are talking about it, they are making attempts to quantify it but we did not want to put our imprimatur on any particular estimate.’
The remarks were seized upon by Tory MP Bernard Jenkin.
He said: ”‘it is not for us to judge at this stage what the impact of “Brexit” might be on the economy and the public finances’ – @OBR_UK.
‘So there!’
In his speech, Mr Osborne said: ‘Over the next few months this country is going to debate the merits of leaving or remaining in the European Union, and I have many colleagues whom I respect greatly on both sides of this argument.
‘The OBR correctly stay out of the political debate and do not assess the long term costs and benefits of EU membership.
Mr Chote’s intervention was seized upon by Bernard Jenkin, a leading eurosceptic on the Conservative benches
‘But they do say this, and I quote them directly: ‘a vote to leave in the forthcoming referendum could usher in an extended period of uncertainty regarding the precise terms of the UK’s future relationship with the EU.
‘This could have negative implications for activity via business and consumer confidence and might result in greater volatility in financial and other asset markets’.’
Mr Osborne added: ‘Britain will be stronger, safer and better off inside a reformed European Union.
Following the Budget speech, Vote Leave Chief Executive Matthew Elliott said: ‘There is one budget the Chancellor didn’t touch today – the £350 million of taxpayers’ money he hands to Brussels every week.
‘Nor could he cut taxes like VAT which we’ve given up control of to the EU Commission.’
‘Disappointingly, the Chancellor sought to politicise the OBR and drag it into his campaign to keep us in the EU despite the OBR making clear that it was not making a judgment about the referendum.
‘If we want to take back control of our economy and our democracy so the Government can spend our money on our priorities, the only safe option is to Vote Leave’.
Mr Osborne infuriated many of the Tory MPs ranked behind him when he used forecasts from the Office for Budget Responsibility to make his pro-EU case