It comes after at least 221 migrants have attempted to cross the Channel to England since the start of November.
Most recently, 12 people were detained off the coast of Dover in the early hours of Friday morning.
Officials on both sides of the Channel have warned of the dangers of crossing what is the world’s busiest shipping lane in a small boat. Police have likened the journey to trying to “cross the M25 at rush-hour on foot”.
Bridget Chapman, from the charity Kent Refugee Action Network, said the situation was in part a result of UK measures to “beef up the security around Calais”.
“We’ve put a big fence up to prevent people from accessing trains and lorries and people are resorting to other methods to get here,” she told the BBC.
“It’s winter, but the weather has been quite good. And I expect people traffickers are exploiting people, saying, ‘You know, things are going to tighten up after Brexit, you need to go now.'”
British and French authorities have both said the rise in crossings is the result of “organised criminality” and “mafia networks”.
He said: “We need to make it really clear to the migrants and the gangs that if you try and do this you will be detected early, either as you’re preparing to leave or as soon as you’re in the water, and you’ll be returned to France.”