A truckload of suspected illegal immigrants were caught making their way up the M1 towards Hemel Hempstead.
Police intercepted the lorry, which was carrying 17 people believed to have entered the UK illegally, just off the motorway shortly after 4pm on Saturday (August 8).
The men, from Vietnam, were taken into custody by Herts Police before being handed over to the Home Office for investigation.
A spokesman said 15 of the group are claiming to be minors and will need to be age assessed. If found to be aged under 18 they will be passed into the care of social services.
Police, who stopped the lorry close to J9 of the M1 at The Watling Street Truck Stop, arrested the driver - a 40 year old man from Poland on suspicion of assisting people entering the UK unlawfully.
A Home Office spokesman said: “Our immigration enforcement teams work closely with the police and other agencies to tackle criminal gangs that smuggle migrants into Britain. And we continue to strengthen border security to stop illegal migrants entering the UK in the first place.
“Last year Border Force and the French authorities foiled nearly 40,000 attempts to cross the Channel illegally — more than double the year before. We use the latest technology and intelligence leads to target the organised gangs behind this criminality.
“The Immigration Act of 2014 made it harder for people to live in the UK illegally. The new Immigration Bill will build on this and we will take tougher action on those who shouldn’t be here, by rooting out illegal immigrants and boosting deportations.”