British Prime Minister David Cameron is expected to caution that the United Kingdom’s exit from the European Union would trigger surge in refugee camps across Southeast England, according to reports Sunday. Cameron will put forth the argument after he calls a date to hold an in-out referendum — expected to be set later this month — on the U.K’s future in the EU, the Telegraph reported.

Cameron will likely suggest that if Britain exits (Brexit) from the EU, the deal that permits British border guards to check passports in France could be dismissed. This means that asylum-seekers would not encounter a British border official until they arrived on British soil, according to the Telegraph. As a result, this could lead to establishment of camps, like the infamous France’s "Calais jungle" in southeastern England, the prime minister is expected to warn, the newspaper reported. The Calais jungle is a moniker given to a refugee camps in northern French town of Calais, where asylum-seekers live while they attempt to enter the U.K.

Under current agreements, which were signed in 2003, the U.K. is allowed to carry out border checks at French ports. If Brexit happens, Cameroon is expected to caution that, France will cancel the deal. "The French would love to pull out of the arrangement," a senior Conservative Party source told the Telegraph. "We will be telling people — look; if we leave the EU the Jungle camp in Calais will move to Folkestone [southeast England]. That is not something people want."

"Our border currently starts at Calais," the source said. "If we are forced to abandon that, there will be real problems. What's happening in Calais will stop being a problem for the French and become a problem for the U.K."

About 5,000 migrants and refugees trying to enter the U.K. are reportedly staying at the Calais camp. However, the 13-year Le Touquet treaty that allows British passport checks on French soil is not necessarily associated with Britain’s EU membership.