The European Union's top diplomat has assured the U.N. Security Council that under a proposed EU maritime operation against the growing wave of migrant smuggling, "no refugee or migrant intercepted at sea will be sent back against their will."

Federica Mogherini addressed the council Monday as the 28-member EU prepares to start making decisions next week on an operation to identify, capture and destroy boats before they are used by migrant smugglers.

Concerns remain even among some council members that the migrants themselves will be harmed, sent back or not be allowed to seek better lives.

The U.N.'s special representative for international migration says about half of the people who reach Europe qualify as refugees.

Peter Sutherland praises a planned EU quota system where countries share the refugee settlement burden.