An unescorted 30-truck convoy carrying 900 tons of food reached one of Ethiopia's worst drought regions this week without incident after the government in Addis Ababa reopened the main road in the north of the country, a spokesman for the U.S. Agency for International Development (AID) said yesterday.

The safe arrival of this and another convoy carrying 500 tons from Addis Ababa in the south to Mekele in the drought-ravaged Tigray Province apparently marks the start of an informal agreement by the Ethiopian government to keep the roads open, but otherwise allow convoys to travel unimpeded and unescorted.

Following an attack by Eritrean rebels last month on a convoy under military escort, U.N. workers and private volunteer groups feared that a military presence increased risk of rebel ambush.

This week the United States made an urgent appeal to the Ethiopian government and rebel troops active in the north to adopt an "open-road, own-risk" policy. The call came after the Ethiopian government closed the main road linking the city of Asmara in northern Eritrea Province to Mekele, after the rebel attack.

Neither AID nor representatives of the Ethiopian government here would confirm that this policy has been adopted. A U.S. official, however, pointed out that "the Ethiopian government cannot acknowledge that they have made such an arrangement because they cannot admit that rebels control the north."

The 1,400 tons of food that reached Mekele this week should last "the next few weeks," an AID spokesman said.

Ambassador Kassa Kebede, the Ethiopian envoy in Geneva who is visiting the United States, said the road is open and will remain open.

Kebede told reporters here yesterday that his delegation had held talks with representatives of AID and the State Department on "the most effective delivery of relief items to drought-affected areas."

"There seems to be an understanding on how to go about it. . . . We will give whatever aid neccessary," he said.