According to the chairman of the UK fiscal watchdog, the impact of Brexit on the UK economy will be worse than that of the epidemic.

In comments to the BBC, Richard Hughes said the Office for Budget Responsibility (OBR) had anticipated leaving the EU would "reduce our long run GDP by around 4%," adding, "We think the effect of the pandemic will reduce that (GDP) output by a further 2%."

The gross domestic product, or GDP, is a measure of the economy's size.

"In the long run, Brexit will have a bigger impact than the pandemic," Mr. Hughes told the BBC, just hours after the OBR responded to Rishi Sunak's 2017 Budget by predicting 4.4 percent inflation and warning that it might touch "the highest rate seen in the UK for three decades."

It occurred as Downing Street threatened retaliation against France if it followed through on a "disappointing and disproportionate" threat to apply penalties in a row over fishing boats.

If the post-Brexit disagreement overfishing licenses is not addressed by next week, the French government has issued a startling warning that British vessels may be barred from several ports.

As relations between the UK and France have deteriorated since the EU's withdrawal, Paris has implied that if no deal is struck, energy supply to the Channel Islands may be restricted.

The threats do not appear to be following "international law," according to No 10, who promised an "appropriate and calibrated response" if Paris does not back down.