Ethiopian authorities have detained more than 70 drivers working with the United Nations, an internal UN email seen by Reuters on Wednesday said, amid reports of widespread arrests of ethnic Tigrians.

The ethnicity of the drivers was unclear. On Tuesday, a UN spokesman said at least 16 UN staff and dependents had been taken into custody in the Ethiopian capital of Addis Ababa. The email said the detained drivers were in addition to the detained employees.

Ethiopian government spokesman Legacy Tulu and Foreign Ministry spokeswoman Dina Mufti did not immediately respond to requests for comment on the drivers’ detention. A spokesman for the UN team in Ethiopia told Reuters it would email a response shortly.

On Tuesday, when asked about the arrests of UN contractors such as drivers a UN spokesman in New York said it was investigating.

The head of the state-appointed Ethiopian Human Rights Commission said on Tuesday that he had received hundreds of reports of tigresses being arrested in the capital.

Police have denied making the ethnically motivated arrests, saying they are only targeting supporters of the rebel Baghayan forces fighting the central government.

Last year a war broke out between the federal government and the Tigre People’s Liberation Front (TPLF), which dominated the ruling coalition in the country.