Federalism in Ethiopia helps maintain unity

* Meles says federal system holds Ethiopia together

* Opposition accuses PM of divide and rule tactics

* Poverty the root cause of divisions, some say

By Aaron Maasho

ADDIS ABABA, Jan 7 (Reuters) - When Meles Zenawi's rebels closed in on Addis Ababa in the early months of 1991, their biggest threat did not come from Mengistu Haile Mariam's army but from a potential breakup of Ethiopia.

The group was about to end centuries of Amhara domination over the country's 70 ethnic groups, but some feared Ethiopia's long marginalised regions might seek to cut loose, as Eritrea eventually did later.

Two decades on, Ethiopia remains one nation. Meles, now prime minister, says the country's "balkanisation" was only averted by an ethnicity-based federal system, although analysts say political authoritarianism and poverty still pose risks.

The model has drawn plaudits from Sudan's President Omar al-Bashir who hailed it as an "example" for Africa at a time his own country, plagued by civil wars since independence, may split after the south votes in a referendum on secession on Sunday.

In a continent where colonial powers arbitrarily drew frontiers indifferent to ethnic divisions, Meles said last month that Ethiopia only survived as a nation by granting autonomy to its provinces -- as well as the right to secede.