“There are no easy solutions — and it is not for the UK and France to solve these problems alone,” British interior minister Theresa May and her French counterpart Bernard Cazeneuve said in a joint letter published in the Sunday Telegraph and the Le Journal Du Dimanche newspapers.
“Many of those in Calais and attempting to cross the Channel have made their way there through Italy, Greece or other countries. That is why we are pushing other member states – and the whole of the EU – to address this problem at root.”
Britain and France said their efforts were not limited to beefing up security, and that they had led efforts to break up the criminal gangs who seek to profit from the flow of migrants.
“Ultimately, the long-term answer to this problem lies in reducing the number of migrants who are crossing into Europe from Africa,” May and Cazeneuve wrote.
The joint plea came as Britain detailed some of the extra security measures agreed with French President Francois Hollande on Friday.
Prime Minister David Cameron's office said Britain would fund a significant boost in the number of private security guards patrolling the French entrance to the Eurotunnel. New fences, security cameras and infrared detectors would also be used to improve security.
French authorities have already increased the number of police in the area.
Church of England Bishop Trevor Willmott, whose diocese covers the English side channel separating the countries, criticized the official response to the crisis.
“We've become an increasingly harsh world, and when we become harsh with each other and forget our humanity then we end up in these stand-off positions,” Willmott said on Sunday in an interview with the Observer newspaper.
Also on Sunday, Italy's coast guard said about 1,800 migrants were rescued from seven overcrowded vessels in the Mediterranean on Saturday, while five corpses were found on a large rubber boat carrying 212 others.
The dead bodies were found on board at the time of the rescue, a coast guard spokeswoman said on Sunday. The cause of death was not yet known, she said.
The Mediterranean has become the world's deadliest crossing for migrants and refugees, with 3,500 thought to have died at sea last year and almost 2,000 so far this year. Many are fleeing poverty and violence in the Middle East and Africa.
Al Jazeera with wire services