Theresa May’s government is secretly considering keeping free movement with the European Union (EU) and implementing “no more checks at the border”, even if the UK walks away from the bloc in a “No Deal” Brexit.

The confidential plans have been discussed by Home Office officials and the UK’s Border Forces at a meeting in January, details of which were leaked to the Business Insider website.

A source close to the Home Office claims the Border Force would have no option but to allow open borders and unlimited migration to continue, as they do not have the staff or infrastructure to enforce more checks or limits without reducing security.

UKIP slammed the revelations on Twitter, highlighting how they “have been calling for a major recruitment and training drive for the Border Agency for years”.

Processing migrants from outside the EU takes around five times longer than EU citizens, and it is claimed Mrs May’s government has not given the border forces the extra resources and time needed to prepare for a clean Brexit.

The options discussed, therefore, include maintaining open borders, reducing checks and managing the risk, or quickly diverting resources to the Border Force.

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In the “worst case scenario” discussed, “ministers [are asked] to tolerate higher risk for security” as full security checks will not be carried out on new arrivals.

In this scenario, the government could agree to implement “intelligence-led controls” whereby only certain individuals coming from the EU would be checked.

An alternative would be to “throw resources” at borders, hiring new immigration officers so that all arrivals can be dealt with as a non-EU citizen if the UK leaves the bloc without a deal.

A Home Office spokesman said: “We have been clear that free movement of people from the EU will end and we will control immigration in the national interest. Immigration from the EU will be subject to UK law.”

“All visitors and UK citizens are already subject to 100% passport and identity checks at the border. This will continue in the future either on a deal or no-deal scenario.”

In June, sources close to the government claimed Mrs May’s aim was to keep the UK in the EU’s Single Market and effectively continue open borders by conceding “freedom of movement by another name”.