The shocking revelation comes in an official report which suggests another sprawling Jungle camp will open at the borders again.
The news will come as a blow to French President Emmanuel Macron who vowed to speed up the deportation process of illegal immigrants in France.
However, the report found that the measures designed to prevent asylum seekers reaching Britain’s shores were flawed.
It called on officials to invest in “real scanners” because the heartbeat technology used to detect migrants in lorries at ports is “not efficient”.
Every week dozens of migrants reach Britain from northern France with the help of people smugglers who charge €3,000 per person, according to The Times.
Sebastien Rivera, general secretary of the Calais Road Hauliers’ Federation, told the paper a sprawling Jungle camp is likely to spring up in Calais again in the near future.
He said: “Our worry is that with these reports there will be a let-up in policing and if that happens we are going to find ourselves with a new Jungle.
“Within a few months or a few years we will be back in the same situation as before.”
Despite Mr Macron’s promises to deport illegal immigrants, the shock document, commissioned by the French interior ministry, found only 1,905 of migrants were booted out of France.
Meanwhile, Calais police made 57,468 checks on migrants found to be in France illegally last year.
Illegal immigrants in France are often deported to Italy and Germany, who are notorious for releasing migrants, which means they return to Calais.
The report comes after Mr Macron demanded an inquiry into the police handling of the Calais migrant crisis when the Human Rights Watch accused officers of systematic violence in a bid to stop another camp forming in the town.
Officials found although some of the 8,000 migrants were violent themselves, police used “unjustified, even disproportionate force”.
The report found that officers used tear gas in a manner “judged to be abusive by spraying it into migrants’ faces.
One migrant claims he was kicked like a football.