The government has been warned many of its measures to ensure security at the UK's borders and the smooth passage of goods through ports like Dover after Brexit will not be ready by next March.

A damning report by auditors highlights plans designed to ensure border operations are not compromised remain behind schedule - including the recruitment and deployment of extra border staff.

It highlights fears that "organised criminals and others are likely to be quick to exploit any perceived weaknesses or gaps in the enforcement regime".

“This, combined with the UK’s potential loss of access to EU law enforcement and national security tools, could create security weaknesses which the government would need to address urgently.”

The National Audit Office (NAO) report lists a series of areas where the government’s preparations for a “no deal” scenario may cause problems.

They include arrangements to allow goods to and from ports such as Dover to operate smoothly.

The report blames “ongoing political uncertainty and delays in negotiations” for hampering the effectiveness of departments’ border planning and delivery.

On a plan by the Border Force to recruit 581 staff, it warns “there is a significant risk that it will not deploy all the staff it plans to recruit by March 2019.”

It warns new infrastructure needed to carry out checks on goods cannot be built by next year’s deadline, saying: “Without this, the UK will not be able to fully enforce compliance regimes at the border on day one.”

And it suggests that as between 145,000 and 250,000 traders would need to make customs declarations for the first time in the event of 'no-deal'.

Of 12 critical systems that need to be either be replaced or changed to manage the border, 11 were at risk of not being delivered on time and to acceptable quality.

Amyas Morse, the head of the NAO, said: “Government has openly accepted the border will be sub-optimal if there is no deal with the EU on 29 March 2019.

"It is not clear what sub-optimal means in practice, or how long this will last.

"But what is clear is that businesses and individuals who are reliant on the border running smoothly will pay the price.”

Dover and Deal MP Charlie Elphicke said: “This report underlines why preparations for no deal should have started the day after the Brexit vote.

"I have long argued that Britain needs to be ready on day one for every eventuality – especially at the Dover frontline.

“The chancellor should commit to significant investment in our borders in the Budget next week.”