One person has been hospitalised after being found in the back of a lorry near the Dartford Crossing in Kent, along with 12 other people.
A South East Coast Ambulance Service spokeswoman said the person taken to hospital was not believed to be in a life-threatening condition.
They said: "Our crews assessed 13 individuals at the scene. One required transportation to hospital and they were taken to the Darent Valley Hospital. "They didn't appear to be in a life-threatening condition. The other 12 were taken to Dover."
Kent Police confirmed they were called to a report of suspected illegal immigrants but said that the immigration service was managing the investigation.
More top news
A woman who attempted to get her idol's full pout was left with hugely swollen lips when her plan went horribly wrong.
All would-be MPs should be forced to tell voters what paid jobs they have and whether they would keep them if elected, Lord Bew has said.
A Para who won the Victoria Cross gave up his military history studies just weeks into the course as he wanted to be a part of it instead.