The World Health Organization (WHO) called on Wednesday for a massive influx of food and medicines into Ethiopia's Tigray region following the ceasefire deal, saying desperately needed aid had not yet been allowed in.

The WHO said people in Tigray needed urgent assistance after two years of bloody conflict, with access to the region severely restricted.

The conflict between government forces and Tigrayan rebels has plunged Ethiopia's northernmost region into a severe humanitarian crisis, with only a trickle of relief having got through.

WHO chief Tedros Adhanom Ghebreyesus welcomed the breakthrough cease-fire agreement reached last week but warned it was already a week on "and nothing is moving in terms of food aid or medicines."

"Many people are dying from treatable diseases. Many people are dying from starvation," he said.

"Even in the middle of fighting, civilians need food, need medicine. It cannot be a condition," he insisted.

"Especially after the cease-fire agreement, I was expecting that food and medicine would just flow immediately. That's not happening," he said.

"Let's give a chance to peace. But we would also urge the immediate delivery of food and medicine."

Tedros is himself from Tigray and was Ethiopia's health and foreign minister.

The government in Addis Ababa and the Tigrayan rebels reached an agreement on November 2 after nine days of talks under the aegis of the African Union in Pretoria, South Africa, less than 48 hours before the second anniversary of the outbreak of the war.

The two parties indicated in a joint statement that they will cease hostilities immediately, disarm the rebels, allow the resumption of aid deliveries and restore basic services.

WHO emergencies director Michael Ryan welcomed the notion of a humanitarian corridor into Tigray, but said experience in other crises showed it was vital that the corridor remained both open "and unrestricted."