Ethiopia's government and Tigrayan rebels agreed on Saturday to facilitate immediate humanitarian access to "all in need" in Tigray, as part of a deal reached at the start of the month to end the brutal two-year conflict in the northern region.

Asked when the aid was expected to arrive, the WHO told AFP in an email that "we hope to be able to access all the people in need in the area in the coming days".

The UN health agency said it hoped to "be able to provide them with food, lifesaving medicines, resupply the health centres with medical equipment, provide children with vital routine immunisation, (and) respond to worsening disease outbreaks."

"People need urgent aid to be delivered to prevent further death and suffering," it said.

Ethiopia's northernmost region -- home to some six million people -- is in the grip of a severe humanitarian crisis due to lack of food and medicine, and there is limited access to basic services including electricity, banking and communications.

The conflict between the Tigray People's Liberation Front (TPLF) and pro-government forces, which include regional militias and the Eritrean army, has caused an untold number of deaths, forced more than two million people from their homes and driven hundreds of thousands to the brink of famine in Tigray.

The WHO, whose chief Tedros Adhanom Ghebreyesus is himself from Tigray, has been stressing the urgency of bringing in aid for months.

During a press conference last week, before the aid deal was concluded, the organisation called for a massive influx of food and medicines, lamenting that aid had not been allowed in since the November 2 ceasefire deal.

"You can imagine that many people are dying from treatable diseases," Tedros said.

"Many people are dying from starvation."