British finance minister Rishi Sunak has ordered an additional set of economic forecasts to be produced by the country's independent budget forecaster.

He has asked that they be published on March 13 - two days after he delivers his first budget. 

"Given the unique circumstances this year, I would like to commission the OBR (Office for Budget Responsibility) to publish a second forecast on the 13 March, to provide a limited update to the 11 March forecast," Sunak said in a letter to OBR Chairman Robert Chote. 

The request reflects the fact that the OBR is legally bound to produce two sets of forecasts per financial year.

Because a planned budget in 2019 was cancelled due to a general election, it has only produced one set in the current period. 

Mr Chote had previously written to Sunak giving him three options to resolve the situation - including a so-called 'limited update'. 

He said a March 13 forecast would include better estimates of the cost of any extra government borrowing announced in the March 11 budget, based on input from the UK Debt Management Office.