The UN has not been able to ascertain as yet why the government detained more than 70 outsourced drivers in Semera in Afar region.
Ethiopian authorities have detained more than 70 drivers working with the United Nations amid reports of widespread arrests of ethnic Tigrayans.
"We confirm that 72 outsourced drivers contracted by WFP (World Food Programme) have been detained in Semera," a UN spokeswoman told Reuters news agency on Wednesday, referring to the capital city of the northeastern region of Afar.
"We are liaising with the Government of Ethiopia to understand the reasons behind their detention."
The ethnicity of the drivers was not clear.
On Tuesday, a UN spokesperson said at least 16 UN staff and dependents had been detained in the Ethiopian capital Addis Ababa.
The detained drivers were in addition to those detained staff, said an email seen by Reuters.
Arrests in capital
Government spokesperson Legesse Tulu and foreign affairs ministry spokesperson Dina Mufti did not immediately respond to a request for comment on the detention of the drivers.
On Tuesday, when asked about the arrest of UN contractors such as drivers, a UN spokesperson in New York said it was investigating.
The head of the state-appointed Ethiopian Human Rights Commission said on Tuesday they had received hundreds of reports of Tigrayans being arrested in the capital.
Police have denied making ethnically motivated arrests, saying they are only targeting supporters of the rebellious Tigrayan forces fighting the central government.
War broke out last year between the federal government and the Tigray People's Liberation Front, who used to dominate the ruling coalition in the country.