The former prime minister dismissed the government’s claims of merely “teething problems”, warning the “bureaucracy” was the inevitable result of leaving the EU single market.
“I hope they can tackle as many of these problems as possible but, ultimately, some of them are because we chose to leave the single market and become a third country,” he said.
In an interview with CNN, Mr Cameron also warned that tax rises “wouldn’t make any sense at all”, ahead of expectations that Rishi Sunak will announce some in next week’s Budget.
And he backed the introduction of so-called “vaccine passports” to enter venues – after Mr Johnson set up an inquiry – saying the idea is “coming”.
“If we want to open up our economy as rapidly as possible, I think there’ll be a number of different ways and places where people will want to know ‘have you been vaccinated’ before you join this event, this party, this whatever,” he argued.
Exports have been hit by a blizzard of bureaucracy, with new requirements for health checks and customs documents – while a ban on shellfish trade is “indefinite”, the EU is warning.
The Independent revealed fears that the appointment of arch-Brexiteer David Frost to lead future talks with the EU will slam the brakes on a possible deal to lift some food checks.
In the interview, Mr Cameron was asked about the “unbelievable problems” Brexit had created, with the economy taking a “massive hit” and the vital services sector excluded altogether.
“I hope the government can address as many of the problems and issues as possible, whether that’s problems faced by British fishermen, whether it’s small businesses finding it more difficult to export to EU countries because of the additional bureaucracy,” he replied.
Next Wednesday, the Chancellor is expected to put the UK on the path to increasing the corporation tax rate from 19 per cent to 23 per cent by 2024, or even as high as 25 per cent.
A windfall tax on the supermarkets, to fund the Covid-19 recovery, is also being considered, it is thought.
But Mr Cameron pointed to the economic situation, saying: “Piling, say, tax increases on top of that before you’ve even opened up the economy wouldn’t make any sense at all.
“I think it’s been right for the government here in the UK and governments around the world to recognise this is more like a sort of wartime situation.”
The intervention came as Philip Hammond, Theresa May’s chancellor, urged Mr Sunak to tell the public “some difficult home truths”.
He called on the government to abandon “extravagant” promises from its election-winning 2019 manifesto, in order to rebalance the nation’s finances.