by Colin Campbell
Home Affairs Correspondent, BBC South East
It is estimated there are 500 Afghans and Eritreans waiting in Calais
Hundreds of migrants are continuing to attempt to get England illegally despite a pledge from French authorities to crack down on it.
The plan was make the port of Calais "watertight to illegal immigration", but an investigation by the BBC appears to show it is not working.
Everyday it is easy to spot the migrants in Calais attempting to get to England by smuggling themselves into lorries.
I spent two days filming in the town and police appeared powerless to stop migrants climbing into lorries outside the port.
And drivers are struggling to prevent stowaways.
These migrants target an area where truck drivers destined for the UK rest and refuel before catching a ferry to Dover.
There are hundreds of migrants currently in the French town.
Some have built camouflaged roadside hides at points where UK-bound trucks must slow down before reaching the port.
We witnessed them pouncing out of the bushes, both by day and night, sprint after the lorries and try to grab their free ride to the UK.
On one occasion we saw migrants open the rear door of a foreign truck heading to the UK.
The driver jumped out armed with a wooden bat and chased the migrants away. But within a few minutes they were back.
I saw no direct intervention by French police.
All the migrants I spoke to said their number one aim is to get to England, and to get there by truck.
Claiming to be from Afghanistan and Eritrea, they appear to be organised and some have mobile phones, despite living in a makeshift shanty town in woods nicknamed "the jungle".
One Afghan man, who said he was called Javed, said he tried every night and would continue "forever".
Some seemed willing to risk their lives and several said their hope was to strap themselves to the undercarriage of a truck.
One eight-year-old boy I spoke to claimed he and his 15-year-old brother fled Afghanistan after their parents were killed by the Taleban. They now try to jump aboard lorries every night.
Several truck drivers told me they believe the problem is worse than ever.
Some simply avoid refuelling or stopping in Calais, but drivers must take regular breaks and some have no option but to stop in or around the town.
Drivers face fines of up to £2,000 for each illegal immigrant caught inside their trucks.
All British drivers we saw were taking adequate precautions ensuring their trailers were properly secured, but they all said they had been targeted.
"They are so quick, but the police do nothing about it," one driver told me. "The police should be here all the time."
Many Afghan migrants are staying in a shanty town in woods outside Calais
French charities estimate there are 500 migrants in the area - 300 afghans and 200 Eritreans.
Many Eritreans are squatting in a large red-bricked property in the town centre, while the Afghans live in a shanty town in nearby woods.
I was invited by some Afghans to look at the conditions in which they live and they are undeniably tough.
The huts are built out of pallets, rugs and tarpaulin sheets and there is rubbish and excrement on the floors.
French police deny doing nothing. On Tuesday it was revealed that police in France arrested a people-smuggling gang alleged to have helped more than 1,000 illegal immigrants into Britain.
But the latest figures show the number of stowaways making it into the UK rose from 1,400 in 2006/7 to 3,300 in 2007/8.
Police say they are actively targeting their resources inside Calais port, where trucks are searched using sniffer dogs and carbon dioxide sensors.
But they say there are no French laws motivating them to intervene if they see migrants jumping on board UK-bound trunks.
The UK Border Agency said it worked night and day with the French police to disrupt attempts by foreign nationals to hide in lorries in the area around the port.
"Our checks within ports make up one of the most secure border crossings in the world," said a spokesman.
"We have hundreds of officers based at ports in France and Belgium, stopping illegal immigrants before they get to the UK.
"In 2008 we prevented over 28,000 attempts to enter the UK in this way.
"We use sniffer dogs and hi-tech methods like heartbeat and carbon dioxide detectors to find well-hidden stowaways.
"We have more than doubled the number of dogs available to us providing coverage 24 hrs a day, 365 days a year. "
Lorry drivers demanded action to stop the increasing numbers of illegal immigrants boarding lorries at Calais for Dover