The UN on Thursday criticised the "unprecedented" number of its staffers being detained in Ethiopia, where the government is cracking down on ethnic Tigrayans amid a worsening civil war.
UN spokesman Stephane Dujarric said nine Ethiopian UN employees and 70 drivers contracted to the world body remain in detention and called for their release.
It was the most significant example of "harassment and arbitrary detention of UN staff" Mr Dujarric said he could recall.
"It is unprecedented in terms of numbers that we're seeing," Mr Dujarric told reporters in New York.
Earlier, Ethiopia's government said UN and African Union staffers in the country do not live "in space" and will be punished for any lawbreaking.
The warning came after the arrest of several UN employees in the East African country for unspecified offences.
Ethiopia declared a state of emergency on November 2 after rebellious forces from the northern region of Tigray and their allies made territorial gains and threatened to march on the capital.
Since then, hundreds of Tigrayans have been arrested in Addis Ababa, families and colleagues say, along with 16 UN staff members whose ethnicity has not been disclosed. Seven of the UN staff were later released.
Police say the arrests are not ethnically motivated.
"UN staff who reside in Ethiopia should respect the law of the country," Foreign Ministry spokesman Dina Mufti told a news conference.
"They live in Ethiopia, not in space. Whether it is a UN or AU staff member, they shall be held accountable."
An Italian aid worker was arrested on Saturday with two Ethiopian colleagues, said Italy's Foreign Ministry and Volontariato Internazionale Per lo Sviluppo (VIS), the organisation that employs them.
Mr Dina reiterated the government's stance that it would not hold ceasefire talks with leaders of the Tigray People's Liberation Front (TPLF) because its forces have not yet withdrawn from the neighbouring Amhara and Afar regions.
He said the other two conditions for a ceasefire were that Tigrayan forces stopped their attacks and recognised the government's legitimacy.
The war in Tigray enters its second year
The AU envoy for the Horn of Africa, Olusegun Obasanjo, and US Special Envoy Jeffrey Feltman, have both visited Ethiopia this week to push for a ceasefire.
Also on Thursday, state-affiliated broadcaster Fana reported that the Ethiopian military, fighting alongside regional forces and allied militias, repulsed attacks by Tigrayan forces near the town of Kemise in Amhara.
The TPLF said last week it had seized Kemise, 325 kilometres from the capital Addis Ababa. Reuters was unable to independently verify that.
Fana also reported soldiers pushed back Tigrayan forces trying to capture the town of Mille in Afar, which lies along the highway linking the port of Djibouti to landlocked Ethiopia.
The TPLF spokesperson did not immediately respond to a request for comment.
The spreading conflict has killed thousands of civilians and forced more than two million people from their homes.
Two diplomatic sources said on Thursday that the European Union is evacuating non-essential staff from Ethiopia. Several other nations have advised nationals to leave.
Agencies contributed to this report.
