New passport checks set to be introduced at Eurotunnel and ferry ports next month could lead to long queues, ferry companies fear.

The checks start on April 8, with passport scans carried out on all those leaving the country to tighten national security.

But a P&O Ferries spokesman said: "Coachloads of little old ladies could end up bearing the brunt of this”.

Eurotunnel's public affairs director John Keefe warned the new arrangement could push the system "beyond the level of capacity".

The new arrangement means ferry companies will have to put every passport through a scanner to provide an electronic record which is sent to the Home Office.

The P&O Ferries spokesman said: "All this is going to take time.

"The approaches to the port of Dover can get extremely busy at peak holiday times and we are concerned that the queues are going to get worse once these checks are introduced.

"We have been working with the Home Office to bring these checks in. We are advising passengers to have their passports ready when they present themselves at check-in.

"We have been asked to do these checks by the Government but we are expected to supply the equipment. We are doing this voluntarily but we have been told that if we don't do it, it will be imposed on us anyway.”

Immigration Minister James Brokenshire told the BBC’s Today programme that people should set out on their journeys earlier on busy days but he rejected the "extreme stories" being spread about the potential impact of the change.

He said: "There are often queues at both Eurotunnel and also Dover in terms of their day-to-day operations.”

Pointing out that there are contingency arrangements in place to deal with any problems, he said: "We don't recognise some of the extreme stories that have been put out in terms of the impact of exit checks on existing processes.

"On busy days I think it is advisable for anyone to set out earlier to ensure that they are at their ports of departure on time.”

Director general of the Border Force, Sir Charles Montgomery, told MPs earlier this year that immigration officers detained 6,000 illegal immigrants in Britain from April to December last year.

The House of Commons Public Accounts and Home Affairs committees have expressed concerns about the effect the new checks will have.