Channel ferry operators laid on extra sailings overnight to clear a backlog that has seen passengers travelling from the UK to France delayed for up to 16 hours.
However, UK interior minister Suella Braverman on Sunday rejected the idea the delays at the start of the Easter getaway were "an adverse effect of Brexit" which ended free movement from Britain to European Union member states.
Despite the additional crossings, Dover Port on England's southern coast said coach passengers could still face waits of up to eight hours before they were able to board a ferry.
"The additional sailings have assisted in clearing some of the traffic, although currently both (ferry operators) DFDS and P&O have two full lanes of coaches in the port before French border controls, with a processing time of about 4.5 hours," a port spokesman said.
"Once coaches are processed in an operator's lane, more are being sent to the port. Currently, the estimated total time is six to eight hours," he added.
P&O Ferries apologised to customers on Sunday, saying some will face waits of four to five hours.
Braverman told Sky News some delays were to be expected at peak holiday times.
"I think we have got a particular combination of factors that have occurred at this point in time.
"This will ease... but it is a busy time of year," she said.
Last summer, the UK government blamed France for failing to adequately staff their border posts at the port of Dover after two days of long delays for all travellers, allegations that Paris denied.
French lawmakers said checks now took longer as Britain has "third-country" status because it was no longer in the EU, and urged that facilities be improved at Dover.
The port said earlier the delays, which began on Friday, had affected coach passengers, with car and freight traffic being processed steadily without undue problems.