Jeremy Corbyn has visited migrant camps in northern France, describing the conditions under which its occupants live as a "disgrace".
In his first foreign visit as Labour leader, Mr Corbyn travelled to The Jungle in Calais, and the Grande-Synthe camp near Dunkirk.
At the Grande-Synthe camp , where more than 2,500 migrants and refugees are sleeping rough in the mud and cold, Mr Corbyn was given a tour of the site and met refugees and aid workers.
"These conditions are a disgrace anywhere. We as human beings have to reach out to fellow human beings," Mr Corbyn said.
The Labour leader's visit comes as the migrant crisis puts increased pressure on the EU -French prime minister Manuel Valls has warned the huge influx of people is putting the Union's future in "grave danger".
Mr Corbyn said the solution to the migrant crisis lay in "dealing with the problem at its source, which are the wars and conflicts".
Speaking about the "dreadful situation" faced by people at the Grande-Synthe camp, Mr Corbyn said:
He said Britain should be part of a pan-European effort to help the people affected by the crisis.
The numbers of migrants and refugees at Grande-Synthe have steadily risen since last October, from around 800 people sleeping rough or in thin tents to around 2,500 in recent weeks.
Most are Kurds from Iran, Syria and Iraq looking to cross to the UK, including some 250 children, according to Medecins Sans Frontieres.