According to MPs, there is a view that the UK ports will have "a big hurdle".
The Public Accounts Committee (PAC) states that government preparations for the prevention of large ports are "in a very tragic manner."
Committee members said that the "real risk" of transportation department (DFT) would not be ready for hard brake.
DF said the committee's conclusions were not "accurate".
In a statement declaring that the National Audit Office's report "failed to reflect on the PAC" "was" disappointing and amazement, "the Department said," The Department has made a significant effort in its efforts.
On 29 March 2019, the UK decided to abandon the European Union.
The PAC is responsible for examining the value of public spending money and controlling the government for providing public services.
A report was looking into the preparations for various government departments of Brexit.
Like previous reports, "How well the government should prepare".
Commission chairperson Meg Hilier said: "The future department for road, rail, maritime and Europe after the broket is unmatched, and the Department of Transport has played a crucial role in the UK.
"In a very short time, there is still to do, no deal related risks have been developed to seriously eliminate obstacles in critical ports, especially at major ports."
The DfT intends to introduce "project brake" to deal with lorry queues on roads up to Dover for cross-travel trips.
The project consists of lorries which climb the M20. You can continue to drive a non-portable traffic.
Analysis: Tom Buriedz, BBC's Correspondence Correspondent
Several criticisms of this report from MPs focused on the idea that the Department of Transport (DFT) was very confident about the preparations for a "transaction". They argue that planning a broader business community is difficult.
Now that talks about transactions with transit companies are now known, now the government has made unrecognized agreements.
Some details have passed away. For example, the European Customs tests that are being blocked by the border authorities require ferry companies to distribute the goods needed at the time.
DFT points out that the preparation of confidentiality should be kept confidential in order to prevent the company from destroying commercial interests.
The £ 35m project of the Department for Traffic Control, free of charge to M20 near Dover, has been published and details of Operation Brook. Other preparation plans have been published, such as ensuring that passengers to the European Union can access international driving. Allow.
Nonetheless, the Public Accounts Committee has not been able to look at the various aspects of the Department's non-contract planning. The report indicates that DLT is "self-confident". There is a risk that our transport infrastructure and infrastructure are not prepared for "a transaction".
Although DFT plans to spend £ 30million on a plan broker, the proposed test has not yet been done.
It's bad to engage with businesses, "she added.
"The secrets surrounding the preparations for the Department and its improvements are secretly poisoned."
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The PAC has suggested that the project will determine any experimental results, and the extensive plans for opening the ports in the UK. The DPT has proposed to write extensive plans for progress before Christmas.
Many members claimed to have been told by the body, "said the chief executive of the Road Haulage Association Richard Burnett.
"The information was patchy, it's often unsupported, confused and usually very low," he said.
"This has left the workers at the sharp end of a bad breeding program, unable to control the distribution network and retain their companies in the business."
The PAC advised the DFT to recognize the "difficult situation" for all the breastfeeding conditions.
Nonetheless, "open up the challenges it faces and the business partners and partners to prepare for preparation in the future".