By Francesco Guarascio LUXEMBOURG (Reuters) - France, Italy and Germany agreed on Tuesday to join forces to identify migrants arriving by sea and to swiftly relocate them across the European Union or send them back to their home countries if their claims for asylum in Europe are rejected. Ministers from the three countries put on a show of unity after the arrival in Europe of thousands of migrants, who make perilous Mediterranean crossings from Libya, strained the resources of Italy and Greece and raised tensions with northern European states that are the destinations of many migrants. “You have three friends in front of you,” French Interior Minister Bernard Cazeneuve said at a joint press conference with his Italian and German counterparts in an attempt to defuse the simmering spat.