Sixteen men have been arrested on suspicion of entering the UK illegally after being found stowed away in a tanker near Milton Keynes.
The men, who presented themselves as Afghan nationals, are in police custody pending transfer to the custody of immigration officers, the Home Office said.
The group was found in an articulated tanker at Newport Pagnell Services between junctions 14 and 15 of the M1.
The Home Office said Immigration Enforcement was contacted by Thames Valley Police on Thursday morning.
Buckinghamshire & Milton Keynes Fire & Rescue Service said firefighters helped remove 16 people from an articulated tanker containing small plastic pellets and carried out a search inside it.