A haulage company boss has called for greater protection for truckers as he warned of a "second summer of crisis" in Calais.
Dan Cook, operations director of Dartford-based Europa Road, said his drivers had been the victims of four attacks in the past two weeks.
He said one driver was attacked by three people with knives at an AS24 station in Calais, leaving him with a cut to his arm.
The assailants ran off when another truck arrived, he said.
On another three occasions, trucks had been stopped on main approach roads to the port by people throwing rocks and trees into the carriageway.
He said: "Once the truck has been forced to stop, significant damage to the truck has taken place as migrants swarm all over the trailer, breaking in, damaging cargo, and secreting themselves on board, only to be later found in part at Calais and part on arrival to our terminal in Dartford (despite dogs on the trailer in both Calais and UK)."
Mr Cook has written to the Road Haulage Association (RHA) calling for action to protect his workers.
He said: "I want to highlight to the RHA the growing number of issues we are seeing in and around Calais, in order to put some further energy behind your petitions to governments.
"Last summer's situation is well-discussed and documented and, after a quieter period, we as Europa, who make around 70 crossings on the Calais - Dover/Folkestone route per day, have seen a significant and dangerous spike in migrant activity.
"In the last two weeks alone, we have had four incidents that personally I find gravely concerning.
"Drivers face real danger and it is vital it is that we safeguard our drivers in what are frightening and intimidating situations.
"As a result we have seen delays to transit, damage and write-off of clients' products and drivers refusing to make the journey via Calais.
"More needs to be done by the combined cross-border authorities to better manage the situation, before more serious harm comes to individuals or drivers.
"I urge the RHA to press hard to both the UK and French government to ensure a safer passage to trucks transiting between the Continent and UK."