A US aid agency is suspending food aid to Ethiopia, because it says donations are being diverted from those in need.
Ethiopian government agencies and the military are behind the scheme, according to a leaked memo.
Some 20 million Ethiopians, who are facing severe food shortages because of war and drought, will be affected.
The United States remains the single largest humanitarian donor to Ethiopia, providing more than $1.8b (£1.4b) in assistance since fiscal year 2022.
The US Agency for International Aid (USAid) is an independent agency that leads the US government's international development and humanitarian efforts.
It said a review of its operations in Ethiopia found what it called a "widespread and co-ordinated campaign" to divert food assistance.
The agency did not publicly say who it believed was behind the campaign.
But a memo prepared by an independent donor group and seen by several news outlets pointed to a "co-ordinated and criminal scheme" apparently orchestrated by federal and regional government entities, with military units across the country benefiting.
On Thursday, USAid said that it could not move forward with the distribution of food assistance until reforms were undertaken.
The agency added that food assistance would resume once it was "confident" that assistance would be delivered to its intended recipients.
Both USAid and US Secretary of State Antony Blinken have raised the matter with the Ethiopian government.
The move comes after USAid and the UN World Food Programme (WFP) froze food aid to the northern Tigray region last month, after the agencies discovered that shipments were being diverted to local markets.
Tigray suffered from dire shortages of food, fuel, cash and medicines during a two-year conflict between forces loyal to Ethiopia's government and the Tigray People's Liberation Front.
Nearly 32 million people in Ethiopia, Kenya and Somalia are currently in the grip of the worst drought in decades.
