MPs would be guilty of a “flagrant dereliction of duty” if the UK crashes out of the EU without a deal a leading business group has said.

UK firms are “frustrated” and “angry” at Parliament's handling of Brexit, Adam Marshall, director general of the British Chambers of Commerce (BCC), will say in a speech on Thursday.

In a blistering attack aimed directly at MPs, Mr Marshall will say: “You have let British business down. You have focused on soundbites, not substance; tactics, not strategy; politics not prosperity,”

“As a result businesses and communities in every part of the UK are still unsure about when the future starts – let alone what it holds.

Businesses have spent three years “going round in circles”, Mr Marshall is expected to tell an audience at the QEII conference centre in Westminster, a stones’ throw from the House of Commons.

“Too many critical questions remain unanswered.

Tariffs in the event of a no-deal Brexit Show all 15 1 /15 Tariffs in the event of a no-deal Brexit Tariffs in the event of a no-deal Brexit Pork There will be tariffs on pork in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Cheese There will be tariffs in place on some cheeses including €22.10/100kg of cheddar, €19.10/100kg of processed cheese and €18.60/100kg on some blue cheeses Getty Tariffs in the event of a no-deal Brexit Milk There will be no tariffs in place on milk Getty Tariffs in the event of a no-deal Brexit Car Parts There will be no tariffs on car parts imported from Europe PA Tariffs in the event of a no-deal Brexit Cars However finished cars will face tariffs of 10.6% Getty Tariffs in the event of a no-deal Brexit Alcoholic drinks There will be no tariffs on alcoholic drinks - except on some rums due to ingredients used in their distilling process Getty Tariffs in the event of a no-deal Brexit Beef There will be tariffs on beef in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Fish There will be no tariffs on many types of fish including cod, haddock, salmon and sea bass Getty Tariffs in the event of a no-deal Brexit Fruit and vegetables There will be no tariffs on almost all fruit and vegetables Getty Tariffs in the event of a no-deal Brexit Chocolate There will be no tariffs on chocolate or other cocoa products Getty Tariffs in the event of a no-deal Brexit Poultry There will be tariffs on poultry in order to protect British farmers Getty Tariffs in the event of a no-deal Brexit Ceramics There will be some tariffs in place on ceramis Getty Tariffs in the event of a no-deal Brexit Steel There will be no tariffs on steel Getty Tariffs in the event of a no-deal Brexit Coal There will be no tariffs on coal Getty Tariffs in the event of a no-deal Brexit Lamb/Mutton There will be tariffs on the meat of sheep in order to protect British farmers Getty

“No one would run a business like this – and it is no way to run a country.”

The government has until 12 April to propose a new Brexit plan if Parliament does not vote through Theresa May’s proposals.

If it cannot agree, the UK will leave with no agreement, an option which is widely predicted to cause large-scale problems for businesses.

“It cannot be right that we leave in a way where government itself predicts there will be mass disruption to businesses and communities,” Mr Marshall is expected to say.

“It cannot be right that some in Westminster shrug off the possibility of shortages that could affect the well-being and the jobs of many people.

“A messy and disorderly exit would not just be deeply irresponsible – it would be a flagrant dereliction of duty.”

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The BCC chief will demand that politicians stop “chasing rainbows” and start making difficult decisions , “however personally or politically difficult they might be”.