The would-be illegal immigrants were discovered during routine checks at around 9pm on Tuesday 21 January as the HGV waited to board a shuttle to Folkestone.
The lorry, which was empty apart from the Albanian nationals, was scheduled to drive to a location in Dover to pick up a load for delivery to France. It had no external lock or seal when it was checked by Border Force officers. The refrigeration unit was not turned on.
The stowaways, 41 male and seven female, all said to be in good health, were handed over to the French authorities. Three of the group were believed to be minors.
The Romanian lorry driver has been arrested by the French border police who will investigate.
Dave Hutchinson, Border Force Deputy Director for South East & Europe, said:
The dangers of using refrigerated lorries and sealed tankers in this way are self evident. The consequences are potentially fatal.
This case demonstrates the complete lack of regard the organised criminals involved in people smuggling have for the individuals concerned. It is even more alarming given that some of those found were minors.
Working with our French and Belgian law enforcement colleagues Border Force is determined to disrupt the criminal networks involved in people smuggling.
Border Force officers based in northern France work closely with the French authorities to help protect the whole of the UK from people attempting to enter the country illegally.
As well as using sniffer dogs, officers also use heartbeat detectors, carbon dioxide probes and physical searches to find people hiding in vehicles.
Border Force is a professional law enforcement organisation which aims to secure the border and promote national prosperity as well as working to cut crime and prevent terrorism.
Anyone with information about immigration crime can contact Crimestoppers on 0800 555 111 anonymously or visit http://www.crimestoppers-uk.org.