The men were found after British officers working at Dunkirk used a carbon dioxide detection probe which indicated the presence of people aboard a Slovakian-registered freight lorry.

The officers searched the trailer and found the men hiding within the load of steel wire.
The stowaways were all handed over to French Border Police, and the vehicle was allowed to continue to the UK.

However, the Bulgarian driver and the haulage company now face a potential fine if they are unable to prove they took steps to secure the vehicle.

Carole Upshall, director for European operations, UK Border Agency, said: "This is exactly why we base so many of our staff in France and Belgium - to stop illegal immigrants before they can reach the UK".

As well as using carbon dioxide probes, our staff also have heartbeat detectors and sniffer dogs to detect the presence of people hiding in lorries".

British officers use hi-tech search equipment to combat immigration crime and detect banned and restricted goods that smugglers attempt to bring into the country.

They use an array of search techniques including detection dogs, carbon dioxide detectors, heartbeat monitors and scanners as well as visual searches to find well-hidden stowaways, illegal drugs, firearms and cigarettes.

Throughout 2009 more than 29,000 illegal attempts to cross the Channel illegally were prevented.