"Hunger has deepened, rates of malnutrition have skyrocketed, and the situation is set to worsen as people enter peak hunger season until this year’s harvest in October," the World Food Program report said.
Across Tigray and the neighboring regions of Afar and Amhara, also affected by the war, an estimated 13 million people need food aid, a 44% increase from the previous WFP report released in January.
Half of pregnant or lactating women in Tigray are malnourished, as well as a third of children under five, leading to stunting and maternal death, the report found.
Even though the delivery of aid resumed after the federal government declared a unilateral ceasefire in March, malnutrition rates have "skyrocketed" and are expected to worsen, the United Nations agency said in an assessment.
The World Health Organization's director-general, Tedros Adhanom Ghebreyesus, who is from Tigray, suggested this week that racism was behind a lack of international attention being paid to the plight of civilians in the region.
The United Nations said that in addition to food, since April 1 only 1,750,000 litres of fuel had entered Tigray, less than 20% of the monthly humanitarian needs in the region, if all supplies were in.
Legesse Tulu, the government spokesperson, did not immediately respond to requests by Reuters for comment on the insufficient delivery of fuel.
Hopes for imminent peace talks between Prime Minister Abiy Ahmed's government and the Tigray People's Liberation Front (TPLF), the party that controls Tigray, are fading, as both parties accuse the other of not wanting to come to the table.
The government said earlier this month it wants talks "with no preconditions", while Tigray's government has called for the restoration of services to civilians first.
The fighting has displaced millions of people, pushed parts of Tigray into famine conditions and killed thousands of civilians.