The United Nations has declared its highest-level humanitarian emergency in conflict-torn Yemen, where it’s estimated more than 80 per cent of the population now needs assistance.

The UN is already scrambling to respond to top-level humanitarian emergencies in Iraq, Syria and South Sudan.

In Yemen, the UN says more than 21.1 million people need aid while 13 million face “a food security crisis” and 9.4 million have little or no access to water. Around 11.7 million have been targeted for assistance under a UN response plan.

UN agencies say airstrikes and ground fighting have killed more than 1,400 civilians since March and displaced more than a million amid shortages of fuel and medical supplies. The World Health Organisation says 3,083 people have died and 14,324 have been wounded.