Work began on Tuesday on a wall to protect the port in the northern French city of Calais from repeated attempts by migrants to stow away on trucks heading for Britain, an AFP reporter said.

The concrete wall, one kilometer long and four meters high, will pass within a few hundred meters of the sprawling migrant camp known as the "Jungle", which charities said now houses more than 10,000 people.

The wall will extend the wire fences that already run down each side of the main road leading to the port.