The first ship carrying grain from Ukraine for people in the hungriest parts of the world has docked at the Horn of Africa port of Djibouti as areas of East Africa are badly affected by deadly drought and conflict.

Food security experts call it a drop in the bucket for the vast needs in the worst-hit Horn countries of Somalia, Kenya and Ethiopia, the nation where this first shipment is going.

But the flow of grain from Ukraine for other hungry parts of the world is expected to continue, with another ship departing Tuesday for Yemen. The UN World Food Program has said it is working on multiple ships.

WFP says this first shipment of grain will be shipped overland to northern Ethiopia, where millions of people have been affected by the country's Tigray conflict, which has now flared up again.

How any of the grain will reach Tigray is now in question as humanitarian deliveries by road and air have been suspended amid the fighting that sparked again last week between Tigray forces and Ethiopian ones. But Ethiopia's neighbouring Amhara and Afar regions also are expected to benefit.

WFP has said the 23,000 metric tons of grain on the first ship are enough to feed 1.5 million people on full rations for a month. But the UN has said 2.4 million in Tigray alone are severely food insecure and that 20 million people across Ethiopia face hunger.

Millions of other people in the Horn of Africa region are going hungry because of drought, and thousands have died. Somalia has been especially hard hit because it sourced at least 90 per cent of its grain from Ukraine and Russia before Russia invaded Ukraine in February.

Food security experts have said it will take weeks for people in African countries to see grain from Ukraine arrive and even longer to see it bring down high food prices that have been a source of despair and protests in multiple nations.

Far more ships carrying grain from Ukraine have been going to richer places like Europe as existing business contracts are fulfilled.