Stuart Machin, who runs the retail giant, said Government-imposed levies now accounted for more than half of his company’s energy costs and had “nothing to do with the price of oil or gas”.

“Over the last few years the ‘policy costs’ on our energy bill have skyrocketed,” Machin wrote on LinkedIn.

“These are the tariffs that [the Government] place on our bills to fund their policies, and have nothing to do with the price of oil or gas. They now make up over half our bill. It’s just not sustainable for UK businesses.”

The comments came as the OECD said Britain faced the biggest hit from surging oil and gas prices out of any major economy.

Inflation will surge more sharply than in other developed nations and wipe half a percentage point off UK growth this year, according to its forecast.

The UK is particularly exposed because of its heavy reliance on imported energy. Oil prices have risen from $70 per barrel a month ago to around $100 today, while natural gas prices have nearly doubled since the start of the war in Iran.

The OECD’s forecast is a blow to the Government, which before the start of the conflict in the Gulf had hoped that cost-of-living pressures would ease this year.

Rachel Reeves, the Chancellor, said the UK had not started the war but that it would have “an impact on our country”. She insisted Labour had “the right economic plan”.

Machin’s frustration with Government policy stems from green energy levies added to the wholesale price of energy.

They include: a so-called renewables obligation, under which suppliers must source a proportion of power from renewable generators or pay a penalty; a scheme that funds clean energy projects; ‘feed-in tariffs’ for small-scale generators and charges that help ensure enough power is on standby.

Beyond policy costs, businesses must also pay network charges, which fund upgrades to Britain’s power network, much of it required to meet Net Zero, and the climate change levy, a tax on non-domestic energy consumption.

A report by the Confederation of British Industry and Energy UK found British businesses were paying 60% more for gas and 70% more for electricity than they did before the energy crisis caused by Russia’s invasion of Ukraine in 2022. That is despite wholesale prices falling “substantially” in the same period.

The OECD predicted that the UK economy will grow by 0.7% this year, far below the 1.2% it forecast for the UK just three months ago. No other country in the G20 suffered a larger downgrade. France and Germany are each expected to grow by 0.8%, a downgrade from December’s projection of 1%.

Only Russia and Italy are on track for weaker growth this year.

At the same time, inflation is expected to jump back to 4%. That is double the Bank of England’s 2% target and well above the 2.5% anticipated before the war.