At least nine United Nations staff members and their dependents have been detained in the Ethiopian capital, the world body said.
A UN spokesperson said on Tuesday that the UN had submitted a request to Ethiopia’s foreign ministry to immediately release those detained in Addis Ababa.UN security officials have visited the detained staff, the spokesperson added.
There was no immediate comment by the Ethiopian government, which has been battling forces from the northern Tigray region for a year.
Tensions between Ethiopia’s government and the UN have been high throughout the war, which has left thousands dead and, according to UN estimates, pushed hundreds of thousands into famine-like conditions.
In late September, the government had ordered the expulsion of seven senior UN officials from the country for “meddling” in its internal affairs.
Ethiopia has said it would expel seven senior UN officials for "meddling" in its affairs, ratcheting up worries over the humanitarian response in the war-torn and famine-threatened Tigray region.
UN Secretary-General Antonio Guterres said he was "shocked" by the decision, expressed full confidence in his staff in Ethiopia and said the UN was engaging with the government "in the full expectation" that the officials would be allowed to return.
The White House condemned the move "in the strongest possible terms" with Press Secretary Jen Psaki calling it "unprecedented action to expel the leadership of all of the United Nations organisations involved in ongoing humanitarian operations.”The expulsions, announced by the foreign ministry, came as Africa's second-most populous country held elections for dozens of federal parliamentary seats, the final round of voting before Prime Minister Abiy Ahmed forms a new government next week.
The seven UN officials, including the local heads of the UN children's agency UNICEF and its humanitarian coordination office, have been declared "persona non grata" for "meddling in the internal affairs of the country", the ministry said in a statement published on its Facebook page.
"According to the letters addressed to each of the seven individuals listed below, all of them must leave the territory of Ethiopia within the next 72 hours," it said.
Ethiopia's northernmost Tigray region has been mired in conflict since November, when Abiy sent troops to topple the regional ruling party, the Tigray People's Liberation Front (TPLF), a move he said came in response to TPLF attacks on army camps.
Fighting ground on for months before Tigrayan rebels retook the regional capital Mekele and government forces largely withdrew from the region.
Since then the TPLF has launched offensives into neighbouring Amhara and Afar regions, while Tigray itself is receiving only about 10 percent of the aid it needs.