Four Dartford truck drivers have been attacked in the last two weeks because of "a spike in migrant activity" at Calais.
Dan Cook, operations director of Europa Road, a division of independent logistics operator, Europa Worldwide Group based in the town, is urging authorities and industry bodies to ensure a safer passage to trucks and drivers transiting between the continent and UK.
He said: "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."
On one occasion last week a driver fuelling at an AS24 station in Calais was attacked by three people with knives. His arm was cut, but they ran off as another truck entered the fuelling site.
Mr Cook added: "On three occasions in the last fortnight we have had trucks brought to a halt on the main approach roads to port by people hurling rocks and trees into the road.
"Once the truck had been forced to stop, significant damage to the truck had taken place as migrants swarmed all over the trailer, breaking and 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) - the UK trade association dedicated solely to the needs of UK road transport operators to urge action.
“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.
"Drivers face real danger and it is vital it is that we safeguard our drivers in what are frightening and intimidating situations.
"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.”"
Because of the attacks Mr Cook said there had been delays to transit, clients products being damaged of written off, and drivers refusing to make the journey via Calais.
The warning comes after a lorry driver was attacked in Calais by someone armed with a chainsaw.