The conflict in Tigray is "horrific", the head of the World Health Organization said on Tuesday.
Tedros Adhanom Ghebreyesus, who is from Tigray, said many people were dying of hunger and that rape was spreading too.
"The situation in Tigray, Ethiopia is, maybe if I use one word, horrific, very horrific - 4.5, almost five million people need humanitarian aid, 91% need food aid, and many people have started dying actually because of hunger, and severe and acute malnutrition is becoming rampant," he said at a news conference in Geneva.
He also said the destruction of health services was adding further strain to the crisis.
Many international leaders and aid agencies have been calling for full humanitarian access and an end to the blocking of aid.
But the Ethiopian government said in a statement on Monday that aid agencies had free access to the region.
"There were indeed difficulties in accessing certain areas" due "to security concerns, but this is now resolved," the foreign ministry wrote in a statement.
The statement added that the Ethiopian government had pledged to investigate the rights violations, denouncing "unjust and unjustified charges against Ethiopia".
The government also denounced what it calls a campaign to exert undue pressure and rejected calls for dialogue with the Tigray People's Liberation Front (TPLF) party, which the government has been fighting since November.
Ethiopian Prime Minister Abiy Ahmed, a 2019 Nobel Peace Prize winner, sent the army to dislodge the TPLF party, who was in power of the northern region and for several months challenged the authority of the federal government.
His government blames the TPLF for starting the war by attacking army camps and has accused it of putting both civilians and heritage sites at risk.
Thousands have been killed and hundreds of thousands have been displaced since Ethiopian and Eritrean troops entered the region.