Well, the African Union has been involved. The problem is that it is not necessarily seen as an impartial body. The African Union is based in Addis Ababa, as you may or may not know. The former Nigerian president, Olusegun Obasanjo, has inserted himself quite actively in this process, but he is seen as too close to the Government of Ethiopia.
I think the African Union is obviously interested in solving this problem. They do not like having the attention on one of its member states. One of the problems is that the African Union is seen as being potentially biased in favour of the government.
If you're asking about a role that is non-African.... I mean, the African Union is often pointed to as an African solution to African problems, but in this case, it's a troublesome one. It may be that other states have to get involved. The issue is that finding a body that is agreeable to both sides is itself a challenge—