A UN spokesman said the Ethiopian government released 34 out of 70 UN’s contracted aid drivers arrested last week.
At a briefing in New York, Farhan Haq said on Monday that 36 others were still being detained.
He hoped that the remaining contract workers and 10 UN national staff arrested by the authorities on Friday would be freed.
Their arrests of the UN staff and contract workers followed the federal government declaration of a state of emergency earlier in the month as rebel Tigray fighters threatened to march on the capital, Addis Ababa.
Thousands of people have been killed and millions others displaced in the year-long war between the Ethiopian authorities and the rebel Tigray People’s Liberation Front (TPLF) fighters.