The head of the European Union's humanitarian aid department has warned that the situation in Iraq is rapidly deteriorating while the world is preoccupied with crises elsewhere.

Jean-Louis de Brouwer told The Associated Press that the number of displaced people in Iraq has quadrupled in the last year and shows no signs of decreasing, adding: "The worst is still to come."

There are 2.7 million people internally displaced in Iraq, where government forces are struggling to wrest back vast areas of the north and west seized by the Islamic State group last year.

In recent weeks another 100,000 have been displaced by fighting in and around Ramadi, in the western Anbar province.

De Brouwer said "there is not just donor fatigue but donor exhaustion."