Police surround the truck, which had been carrying human cargo, outside Peterborough
The men are believed to have travelled thousands of miles from Eritrea in East Africa.
The lorry driver alerted police after suspecting there were people hiding in the back.
The vehicle was stopped by officers near Peterborough, Cambs, at the weekend.
The migrants were taken to an asylum centre where their cases will be scrutinised by immigration officials.
One of the apprehended migrants is searched
The discovery comes just days after a Daily Express investigation revealed the true scale of the people-smuggling trade from France to the UK.
Our team in Steenvoorde, northern France, witnessed traffickers loading illegal migrants on to lorries in broad daylight at the rate of almost one vehicle every hour at a motorway service station.
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Hundreds of truckers use the Aire de St Laurent services on the A25 motorway near Steenvoorde – 25 miles from Dunkirk and 40 miles from Calais – as a final stop before crossing the Channel.
It has become a hotspot for One of the apprehended migrants is searched people-smugglers.