Kwarteng had originally planned to publish his debt plan alongside its medium-term fiscal plan on 23 November.

In a letter to MP Mel Stride, who is chair of the Treasury Select Committee, he said that the new forecast date would allow the Office for Budget Responsibility (OBR) to “capture data releases” such as recent quarterly national accounts and “blue book revisions”.

Blue book is what the annual national accounts are called by the Office for National Statistics.

Kwarteng added: “It will allow for a full forecast process to take place to a standard that satisfies the legal requirements of the Charter for Budget Responsibility enacted by Parliament and that also provides an in-depth assessment of the economy and public finances. And it will provide time for the medium-term fiscal plan to be finalised.”

He continued that Prime Minister Liz Truss and himself had met the OBR’s budget responsibility committee on 30 September to discuss economic and fiscal outlook and they would “continue to work closely together throughout the forecast process and beyond”.

Mini budget turbulence

Kwarteng’s mini Budget in September caused much disruption in the financial markets, with the pound falling to a record low and the Bank of England having to take an intervention into the bond market.

This in part lead to the soaring swap rates, and lenders consequently pausing lending, removing and repricing products.

MPs had urged Truss and Kwarteng to allow the OBR to reveal its forecasts as soon as possible to assuage the markets, including Stride.

In his letter, Kwarteng said that upon his arrival in office he had received a preliminary analysis from the OBR but had since made “significant policy announcements”, including the Growth Plan.

“It is important that a forecast includes a full and final assessment of the impact of policy measures on the economy and public finances and, as such, it would not be appropriate to publish the initial analysis that the OBR provide,” Kwarteng said.

He added that planned “regular engagement” with the committee and he would attend it after the 31 October.