LONDON: Brexit will hit Britain's economic growth more than the coronavirus pandemic in the long term, the head of a UK government body advising on the financial outlook has said.

"In the long term it is the case that Brexit has a bigger impact than the pandemic," chairman of the Office for Budget Responsibility, Richard Hughes, told the BBC Wednesday following a government budget update.

Hughes said recent data showed the impact of Brexit was "broadly consistent" with the OBR's assumption that Britain's exit from the Europe Union would "reduce our long run GDP by around four percent".

He added that the OBR believes "the pandemic will reduce that output by a further two percent."

Britain formally departed the EU at the start of the year, while Brexit has contributed to supply disruptions caused also by Covid.

Using the OBR's forecasts, the British government on Wednesday said UK total output was expected to rebound by 6.5 percent this year before slowing slightly in 2022.

Updating Britain's tax and spend plans, finance minister Rishi Sunak added that the UK economy was on course to return to its pre-pandemic level at the turn of the year.