European Commission chief Jean-Claude Juncker said EU member states have "failed to deliver" on efforts to resolve the migrant crisis, including on a deal to relocate 160,000 migrants from Italy and Greece.

"A number of member states have failed to fully deliver on what we need to do and what needs to be done," Juncker, the head of the executive branch of the 28-nation union and the driving force behind the plans, told a press conference.