Preparations for the possibility of a no-deal Brexit will include up to 150 lorries queuing up near Dover during rush hour to test plans to deal with any disruption caused by new border customs checks, the government has confirmed.

Hauliers in the area will be asked to take part in Monday’s live test of a mass “HGV holding facility” that is designed to deal with any backlog after the UK leaves the EU in March.

In a letter to hauliers, obtained by Sky News, the Department for Transport (DfT) and Kent county council officials say they would run tests during the morning rush hour at 8am, and again at 11am, to “establish the safest optimum release rate of HGVs” from a nearby airfield to Dover along the A256.

It said it would pay for 100 to 150 hauliers from the local area to take part in the test of Operation Brock.

One haulage sector source was skeptical about the robustness of the test: “It is purely academic exercise. How can you possibly mimic with 100 drivers the real situation with 6,000 trucks, many with foreign drivers? I don’t think they will get 150 trucks or companies because it is such short notice.”

A DfT spokeswoman said: “We do not want or expect a no-deal scenario and continue to work hard to deliver a deal with the EU. However, it is the duty of a responsible government to continue to prepare for all eventualities and contingencies, including a possible no deal.

“We will be testing part of Operation Brock to ensure that, if it needs to be implemented, the system is fully functional.”

Congestion at the Channel ports caused by the reintroduction of customs checks on goods has been one of the most commonly cited negative impacts of a no-deal withdrawal from the EU at the end of March.

However, a poll of Conservative party members has dealt a new blow to Theresa May’s chances of getting her deal through the Commons, with 57% of grassroots Tories saying they would support leaving the EU without an agreement despite the customs checks concerns.