The truck had been carrying 31 people, reportedly from Pakistan, when it was inspected by authorities in southern France. The latest discovery comes after dozens of migrants were found dead in a truck near London.
Officers carrying out a routine traffic check in southern France uncovered dozens of migrants in the back of a truck on Saturday, the public prosecutor's office in Nice said.
Some 31 people, including three unaccompanied minors, were found in the truck during a vehicle spot-check at a toll booth near La Turbie, near the border with Italy.
Prosecutors said that all 31 people on board were Pakistani nationals. The driver of the truck, who is also from Pakistan, was arrested by French authorities.
The migrants were handed over to Italian authorities, the Nice-Matin newspaper reported.
Prosecutors will now try to determine whether a human smuggling ring is behind the operation. Should that prove not to be the case, the driver of the truck will be charged with aiding and abetting illegal immigration, news agency AFP reported.