In a possible sign that fractious sub-clans of Somalia's Hawiye tribe may be uniting to oppose Ethiopia and Somalia's interim government, a top Islamist leader and the deputy prime minister of the interim government have jointly issued an ultimatum for Ethiopian troops to leave Somalia immediately or face an all-out war.  VOA Correspondent Alisha Ryu has this report from our East Africa Bureau in Nairobi.

Ethiopian soldiers walk past a technical vehicle of the Islamic Courts movement in Mogadishu, 18 Jan 2007

The ultimatum, issued late Wednesday by Islamist leader Sheik Sharif Sheik Ahmed and Hussein Aideed, was blunt - leave Somalia now or prepare to fight to the death.

The two senior leaders, who are members of the Hawiye clan that dominates the Somali capital, Mogadishu, spoke after holding talks in Eritrea, Ethiopia's archrival in the Horn of Africa. 

Aideed said that Somalis would unite against what he called "the brutal occupation" of Ethiopia, whose forces helped oust Somalia's powerful Islamist movement from power nearly four months ago.

Ahmed and Aideed were joined by Sharif Hassan Aden, the interim government's former speaker of parliament.

Sharif Hassan, who belongs to another major Somali tribe called the Digil-Mirifle, has held talks before with Sheik Ahmed and other Islamist leaders.  The former parliament speaker was removed from his post in January for being too conciliatory toward the Islamists, and on Tuesday, he was among 30 dissident Somali lawmakers fired by the government.   

But Hussein Aideed's motivation for joining Sharif Hassan and Sheik Ahmed in condemning Ethiopia's intervention in Somalia is not yet clear.

Aideed, a former factional leader with a long history of changing sides for political reasons, still holds the posts of housing minister and deputy prime minister in the interim government.  He had initially praised Ethiopia for its role in defeating the Islamic Courts Union, which Aideed said was controlled by extremists with ties to al-Qaida.

A South African-based expert on Somalia, Richard Cornwell, tells VOA that he sees Aideed's apparent alliance with the Islamists as a possible sign that Hawiye's numerous sub-clans have decided to unite to oppose the interim government.

Aideed and Ahmed belong to different Hawiye sub-clans, who have fought each other for control of Mogadishu for more than 15 years. 

But Cornwell notes that since the Transitional Federal Government (TFG) took power in Mogadishu in January, the Hawiye clan has become alarmed over moves by the Ethiopians and the government to forcibly disarm them and to give key security posts to members of President Abdullahi Yusuf's clan, the Darod.

"I think what has happened is that the TFG-Ethiopian assault on Mogadishu is cementing the Hawiye back together," he said.  "A large part of the Islamic courts movement was always based on the Hawiye.  So, basically, it has melted back into the clan structure.  What we could well be looking at, if things turn nasty, is a Hawiye-Darod civil war.  Unless the international community manages to understand that they must not continue with this unquestioning support of the TFG, we are going to head down the path of civil war."

Another Somali observer in the United States, J. Peter Pham, says the withdrawal of Ethiopian forces from Somalia may be a positive move, if it meant that Somalia could form a new government with a broader base of support.

"If those forces withdrew, that will be the end of the TFG," he noted.  "However, I would not see that necessarily as the worst possible outcome.  One of the TFG's on-going problems is that it is not a representative institution of Somalis.  If the TFG falls, so be it, and let the Somali people themselves decide what they want."

Both analysts warn that a prolonged civil war between the Hawiye and the Darod could give extremists inside the Islamist movement an opportunity to once again push their agenda of uniting the country under a radical form of Islam