A no-deal Brexit would be disruptive not only for Britain but many businesses in the European Union as the free flow of goods is tripped up by the reimposition of regulations and borders.
Leaders of trade associations urged their members to prepare for the worst and expect chaos if Britain exits the EU on March 29 without any agreement on at least transitory trade arrangements.
A no-deal Brexit "is absolutely unacceptable for the European business community," said Markus Beyrer, head of the BusinessEurope. "It will create chaos and disarray and must be avoided."
Auto manufacturers have supply chains that criss-cross the Channel and Britain is the destination of around 10 percent of vehicles assembled on the continent.
"Sometimes certain parts travel five or six times across the border between the UK and the continent," said economist Carsten Brzeski at ING Diba.
The European Federation of Pharmaceu-tical Industries and Associations (EFPIA) warned "there are very real, tangible and immediate threats to patient safety and public health in both the UK and across Europe" from a hard Brexit.
Analysts warn the most immediate threat is border snarls causing ruptures of supplies, while longer-term manufacturers in both the UK and the EU will no longer benefit from being in the same regulatory environment with mutual recognition of approvals for drugs.
Under the latest guidance from the EU, current flight schedules should be unaffected from a hard Brexit. But the industry is concerned that this could crimp the sector's ability to respond to customer demand going forward.
"A 'no deal' Brexit could lead to a cap on flights that will stunt important economic opportunities and may lead to higher prices for consumers," the International Air Transport Association warned.
A no-deal Brexit means passengers transiting through EU airports will risk having to go through security controls again, potentially causing delays.
Ports will need to build or expand facilities to conduct inspections as well as collecting different taxes.