Council chiefs are calling on the government to ensure border controls are kept at Calais to stop illegal migrants and asylum seekers entering the UK.

The leaders of both Dover and Shepway councils have warned the Brexit minister David Davis that bringing back controls to the UK as part of any deal risks increasing the numbers that would have to be dealt with and become the responsibility of councils already under pressure.

A joint letter signed by south east councils says: “Dover and Shepway are keen to see border controls staying in France for vehicles and passengers inbound to the UK.

"The controls are currently at Coquelles for the Channel Tunnel and at Calais Port for the Port of Dover.

"The alternative – repatriating the incoming borders to the UK in less than two years’ time – would require significant investment in the land and infrastructure required to carry out checks on UK soil.

“Moving controls to the UK also has potential to increase the number of illegal migrants and asylum seekers arriving if the checks in France are removed or scaled back.

"This would increase the pressure on local authorities nationally – and the Home Office itself – by raising the demand for asylum dispersal places.”

The letter also warns any failure to secure alternative arrangements for customs checks could impose “significant new burdens on local authorities.”

These could include a “substantial increase in port health responsibilities if the inspection of foods from the EU is required post-Brexit.

"This would increase the need for staff and processing areas and would slow the transit of freight.”

That could lead to delays getting products to consumers and risk damaging the health of the retail, hospitality and farming sectors, the letter says.

Councils also flag up the potential for delays for passengers after 2019 without a suitable system to check them.

“Without a viable E-system to help process non-UK passengers, ports and airports will have to manage lengthy queues, which risk deterring both business travellers and tourists.”

The current agreement for border checks to be carried out at Calais is a result of a bi-lateral treaty between the UK and France.

However, there have been warnings from the French authorities and regional leaders that they would look to end it once the UK leaves the EU.

The Department for Exiting the EU has been contacted for comment.