Paris: Thirty-one migrants, including a three-year-old child, were discovered on Friday unharmed in a refrigeration truck in northern France's Pas-de-Calais region.

A total of 30 Syrian refugees and a Vietnamese national were found on highway A16 in a vehicle designed to carry frozen food, Xinhua news agency reported.

Since June, about 3,500 refugees have been camping out in the northern port city of Calais, looking to cross to the British capital.

France pledged to welcome up to 30,000 refugees, mainly from Syria, over the next two years and urged joint responsibility in addressing the refugee crisis.