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
Congress has voted overwhelmingly to impose new sanctions against Russia - and curb Donald Trump's ability to waive the penalties.
People were forced to take shelter overnight on the beach near St Tropez as firefighters battled raging forest fires.
A band of wet and rather windy weather will move east across the British Isles, giving some heavy bursts of rain in the north.