The government has been urged to do more to clarify arrangements for new post-Brexit border checks in Kent.

It follows a suggestion there could be a ‘soft launch’ or ‘phased introduction’ of new passport controls, designed to avoid long delays lasting potentially several hours.

A report by the National Audit Office (NAO) says the total bill after five postponements of new measures - including on food checks - was almost £5 billion.

The NAO said the government had itself estimated “it will have spent at least £4.7 billion to implement new arrangements and improve the management of the border, but has not yet specified when it intends to have a full regime in place”.

It also found that repeated delays in introducing import controls, and difficulties forecasting requirements, had resulted in government expenditure on infrastructure and staff that were ultimately not needed.

Meanwhile, late announcements about policy and uncertainty about the implementation of controls have also reduced the ability of businesses and ports to prepare for changes.

Speaking before the NAO report was published, Kent County Council leader Roger Gough said that since flagging up potential problems in January, there had been greater clarity from the government - but more was required.

Cllr Gough said: “I think there are a lot of unknowns and some really big challenges for everyone involved and a lot of different players.

“The government has been much more dynamic and there is a lot more that needs to be in place to get this manageable.”

He also cautioned that the responsibility for some changes did not lie with KCC but with other agencies

“There are a lot of things here we can’t do,” he said.

“A key question is what can be done. It is seeing what resources there are for others, like the French police. I don’t think anything is clear about this pause or ‘soft launch’.”

The NAO said: “The repeated delays in introducing import controls, and difficulties forecasting requirements, have resulted in government expenditure on infrastructure and staff that were ultimately not needed.”

New ‘exit and enter’ arrangements for travellers and businesses are due to come in in October but there have been suggestions of another delay. Biometric testing will mean travellers will need to register some form of ID before they depart.

More than 100 special kiosks are being put up at the Eurotunnel site at Folkestone to help with fears of congestion on the roads.

Meanwhile, biosecurity measures to stop potentially contaminated food products from getting into the UK, introduced at the end of April, have continued to spark arguments over whether they should be conducted at a site in Dover or at the inland border facility at Sevington, near Ashford.

In the latest row, the Port of Dover Health Authority has accused the Department for the Environment, Food and Rural Affairs of deliberately misrepresenting its position and has called for an urgent meeting of the Efra select committee of MPs.

Bosses say in a letter that the current arrangements are insufficient to safeguard the border and stop potentially hazardous food products coming into the UK.

As a result, the country is exposing itself to “an entirely needless increased risk of animal and public health outbreaks”.

The NAO recommends that full border controls operate at all ports as soon as possible, with government departments and devolved administrations collaborating where necessary.