French President Francois Hollande has warned that should Britain leave the European Union, there will be consequences for the refugee crisis currently gripping Europe.

“I don't want to scare you but to tell the truth, there will be consequences... including on the question of people... the way in which we manage migration issues,” Hollande told reporters after a meeting with British Prime Minister David Cameron in the northern French city of Amiens.

The warnings came hours after the French Economy Minister Emmanuel Macron said Britain’s potential exit from the EU, known as Brexit, would make it harder for London to block refugees from crossing the Channel, to Britain’s southern coastline.

Hollande, speaking along Cameron, also called for children in the French town of Calais to be reunited with family across the Channel.

“When these youngsters have a family tie in the United Kingdom, they should go to the United Kingdom quickly and efficiently," he said.

Cameron also agreed that the current system of monitoring the movement of refugees through the Channel had to work “better, more speedily,” saying, “If someone has direct family in Britain and applies for asylum in France they can come and rejoin direct family in Britain.”

Many in Britain fear that if border control agreement with France is cancelled, camps similar to the so-called Jungle shanty at Calais could soon spring up on Britain's southern coastline.

“The day this relationship unravels, migrants will no longer be in Calais,” said Macron ahead of the France-UK summit.