The International Monetary Fund (IMF) will publish a full assessment of how Brexit will affect the UK economy less than one week before Brits go to the polls on 23 June.
While issuing a stark warning that a vote to leave the EU could trigger a recession – the second in two days after Mark Carney's comments sparked a bitter row with former chancellor Lord Lamont – Lagarde said there would be plenty more numbers on the way, and pencilled in 16 or 17 June for the document to land.
This latest development will provoke outrage among campaigners who will be dismayed that the IMF is set to wade into the debate in such a high profile manner potentially six days before the referendum.
Vote Leave has repeatedly attacked the IMF for talking the UK economy down and yesterday Lord Lamont issued a stinging attack on Mark Carney for compromising his independence with Brexit warnings.
IMF has talked down the UK’s economy before and has been wrong in past forecasts about the UK and other countries. #VoteLeave— Vote Leave Media (@Vote_LeaveMedia) May 13, 2016
Lagarde suggested the "selected issues paper", which will be distributed to the IMF board ahead of its meeting on 15 June and published at the discretion of the UK government in the few days after.
It is likely to include an assessment of how the UK economy would perform outside of the European Union under a number of different scenarios, including the short-term shocks to things like equity prices, the value of the pound, economic output, unemployment rates and wages.
It will also discuss how Brexit will affect other European and global economies.
The IMF chair dismissed the idea that the Treasury had any interference in the publication of the report.
"Heck no" was Lagarde's answer to a question about whether the IMF was conducting its research on political grounds.
She also said that the IMF would be prepared to admit if it was wrong, but said the vast weight of independent analysis suggested that Brexit would have a negative affect on the UK economy.
"Sometimes we are wrong … that is true. We are one of the few organisations that admit when we are wrong."
You're telling us!— Leave.EU (@LeaveEUOfficial) May 13, 2016
Wrong in Greece
Wrong on the Euro
Missed the global financial crisis
Why should we listen now? pic.twitter.com/fwLOGBoanu
"We are not doing it out of politics. This is not the job of the IMF.
"It's not just a domestic issue. I know it is a big domestic issue, but it's an international issue," Lagarde said.
"I do not think I have visited a country anywhere in the world where I have not been asked: 'what will be the economic consequences of Brexit?'"
IMF says a vote to leave will cost us money, leaving us less to spend on public services. Also sharp drop in house prices and equity.— People's Vote HQ (@peoplesvote_hq) May 13, 2016
Lagarde was speaking at the Treasury as the IMF published its latest snapshot of the health of the UK economy, the conclusion of its so-called Article IV analysis.