Eight suspected migrants were filmed climbing from a lorry after throwing glass bottles on to a motorway.
The men climbed up an embankment after being let out the back of the lorry near the Dartford Crossing.
HGV driver Sam Hollamby said he saw “arms coming out the side” of the lorry in front as he drove along the M25 in Kent at about 14:00 GMT on 25 January.
Sajid Javid declared a “major incident” after about 220 people crossed the Channel in small boats in two months.
Charities have said migrants were forced to take boats after increased security in Calais made it more difficult to enter lorries.
A BBC investigation has found that migrants trying to enter the UK by lorry are spreading their efforts from Calais to ports across Europe.
Mr Hollamby said: “I saw a duvet being held out the side, I assume trying to catch the driver’s attention. Then they started chucking glass bottles out.
“The driver then pulled over and let them out.”
He added: “I called the police and let them know, but they still haven’t called me for the video. They didn’t seem too bothered.
“They asked for a description and I said ‘I’m not being funny, but I’ve got a video here that will show you exactly what they look like’.”
Kent Police said it was a matter for Home Office Immigration Enforcement.
The Home Office has been contacted for comment.