The UK companies have charged the government to "leave them out to dry" if Brexit is an accident.
With less than 50 days to 29 March when the UK is due to leaving the EU, British Commerce (BCC) states that 20 key issues are still unresolved.
As skilled workers between the UK and the EU are moving, which regulations will continue and what trading businesses they still have to be recognized, the BCC says.
The government said that it was focused on a & # 39; obtaining agreement for its Brexit contract.
"The best way to support our economy is to protect jobs and prove businesses and individuals as we abandon their & # 39; agreement we have agreed with the EU.
"We focus on protecting the necessary changes to ensure that the negotiations go through the Parliament," said the government spokesman.
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Theresa May is currently seeking changes to her & # 39; Brexit's case with the EU after being rejected last year, is the biggest loss for a government to sit.
The prime minister must approve an agreement with the Parliament by March 29 to Brexit not to; avoided, and so the UK will set out the World Trade Organization rules.
The Labor Party has complained about her to run down to her; clock. He says Mrs May is expecting to delay her. final vote that is permissible in terms of its transit agreement she has agreed with the EU to last time; possible, until the MPs have a strong discretion between its contract and agreement.
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The BCC – which represents thousands of companies – says that the members are "extremely worried" that the UK is not ready for every event.
A business business lobby group also warned that the clarity of what already happens "would prevent investment and growth".
"There is a real danger that the lack of clear and active information from the government will leave companies, the people and their communities out to dry," said BCC, general director of Adam Marshall.
Mr Marshall said companies were still "in the dark" about essential issues, including contracts and practice targets.
"Businesses need answers, they can set decisions, whatever the product," he said.
The BCC has been published on the list of 20 business queries to respond. They include companies of choice and choice of goods between the UK and the EU after the end of the year. March and have any targets for export.
A business agency warning is a & # 39; after being a ruler of the English Bank, Mark Carney, had previously decided to MP to resolve the street in Brexit.
Mr Carney warned him that Brexit would escalate "economic" at a time when China's economy slowly and trading initiatives are rising.
"It's good for everyone, probably everywhere" that a Brexit solution has been found, he said.
Earlier this week, official figures showed that the United Kingdom economy had expanded at the lowest annual level in last year's six years, with many economists expanding it; blamed Brexit to slow it down.