One person suffered minor injuries after a coach driving onto a P&O ferry at Calais was lifted into the air by a boarding ramp.
Pictures from the scene show the vehicle suspended over the ramp on the Spirit of Kent.
Staff can then be seen trying to rectify the problem.
Darren Proctor, Secretary of the RMT Union: ”As many people are heading off on holidays, to those considering using P&O Ferries after the way in which they treated their hard work.
"(This) is ANOTHER example of what diluted safety looks like.
"When you sack your employees and replace them with exploited agency workers from around the globe, you cannot replace experience, knowledge or familiarisation.
"This could be you and your family on that bus.
"This could be your car.
"Whilst they are undercutting other operators this is why they are charging less, because they are cutting corners, exploiting seafarers and jeopardising the safety of the travelling public.”
A P&O Ferries spokesperson said: "We are writing in response to the outrageous and misleading claims made by some individuals regarding an incident on Saturday, in which a bus was damaged in Calais when boarding one of our vessels. The bus in question was in the control of port authorities at the time of the incident.
“We can state categorically that what happened was not related in any way shape or form to changes in our crewing model. Although we are never complacent, we have hired high-quality, experienced seafarers who have familiarised themselves with all our vessels and are working to the highest standards.
“To suggest otherwise is grossly irresponsible and has the effect of undermining our business, which employs 2,200 people across Britain, and on which hundreds of thousands of tourists are relying for their holidays this summer.”
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