Businesses need to know what will happen after Brexit as they consider a "cliff edge scenario" where trade suddenly transforms, the government has been told.

Paul Drechsler, president of the CBI, will highlight areas of uncertainty for businesses, such as access to Europe's markets and workers.

He will tell the business group's annual conference in London on Monday that companies wanted a "smooth" Brexit, avoiding "cliff edge" issues.

He will tell a thousand business people: "Businesses are inevitably considering the cliff edge scenario - a sudden and overnight transformation in trading conditions.

"If this happens, firms could find themselves stranded in a regulatory no man's land and, even if our legal obligations are clear and in place, there would also be real, practical implications.

"Our ports, airports and logistics firms, if faced with new trading rules, could suddenly need new and potentially complex paperwork, which would take more time and money to process.

"As a result, they'd need more warehouses to store more goods on site and more supply roads for the vehicles waiting to deliver them. At short notice - this would be impossible."

Mr Drechsler is also expected to warn that many see business as run by a "privileged few", playing by different rules to everybody else.

"We need to acknowledge that there have been unacceptable transgressions, which have made people question the value of what we do and our right to do it," he will say.

"These cases are exceptions, but they're shaping people's view of all of us. On a range of issues we need to show not just that we're listening to people's concerns, but that we're acting on them.

"We need to show people that business is on your side."Mr Drechsler, who is chairman of social mobility charity Teach First, will add that business must remain "calm, confident and constructive" over Brexit.