Rival Somali factions prepared for battle on Thursday after the collapse of peace talks aimed at averting an all-out war that many fear could ignite a regional conflict across the Horn of Africa.
As they traded barbs and blame for the failure of the peace talks here in the Sudanese capital, Somalia's powerful Islamists and weak interim government reinforced front-line positions on the ground and kept up artillery duels, witnesses said.
With tensions soaring and uncertainties for a proposed mid-December date for a resumption of talks, the United Nations special envoy for Somalia warned of trouble while neighbouring Ethiopia said the Islamists were "making war inevitable."
"The intransigence of both parties led to the collapse of the negotiations and now there is a risk of clashes," envoy Francois Fall told AFP. "We fear the parties may slide into conflict."
In Khartoum, the Somali government blamed the Islamists for cratering the talks -- which were set to begin Monday but never started -- by demanding the withdrawal of Ethiopian troops from Somalia and the removal of Kenya as co-mediator.
"The Islamic courts are responsible for the failure of the talks in Khartoum," said deputy prime minister Abdullahi Sheikh Ismail, the government's chief negotiator.
"Their pre-conditions showed their desire to turn Somalia into a battlefield," he told reporters. He called for the international community to slap sanctions on Islamist leaders, some of whom are alleged to have ties to Al-Qaeda.
While Islamist and government fighters massed outside the government's seat of Baidoa, panicking terrified residents, Ismail warned that the transitional administration would not allow the Islamists to continue to advance.
"The government ... has the right to take all the necessary action to secure the whole of Somalia," he said.
"We will not sit and watch while criminal acts of the Islamic courts devastate Somalia. Our hands will not be tied. We will act very soon."
The Islamists, meanwhile, blamed the talks' failure on Ethiopia's refusal to withdraw the thousands of troops they said it has deployed to lawless Somalia to protect the government from any Islamist attack.
"The talks collapsed because of Ethiopian troops," said Sheikh Sharif Sheikh Ahmed, head of the executive arm of the Supreme Islamic Council of Somalia (SICS). He maintained that Addis Ababa had deployed 12,000 soldiers.
"They are going to attack us and take our country and that will not happen by the wishes of Allah." Ahmed was speaking in the capital, Mogadishu, to thousands of soldiers from the former Somali army who have vowed to fight for the Islamists.
Ethiopia denies it has thousands of soldiers in Somalia but acknowledges sending military advisers to help protect the weak interim government from the "jihadists," whose rise some liken to that of the Taliban in Afghanistan.
In Addis Ababa, the Ethiopian foreign ministry issued a blunt assessment of the deteriorating situation, blaming "extremist" Islamists for the failure of the peace talks and looming war.
"The extremists who are setting the tone are not for peace. Rather they are making conflict inevitable," ministry spokesman Solomon Abebe told AFP.
The soaring tensions have sparked deep fears that full-scale war is imminent and could draw in Ethiopia and its arch-foe, Eritrea. Many believe the two nations are using Somalia as a proxy battleground for an unresolved bloody border war.
Eritrea denies charges it is backing the Islamists and has sent some 2,000 troops to Somalia and has accused the United States and Ethiopia of preparing to invade the impoverished nation of some 10 million.
Meanwhile, outside Baidoa, about 250 kilometres (155 miles) north-west of Mogadishu, government and Islamist fighters were reinforcing positions about 20 kilometres (12 miles) apart. The two sides are locked in a stand-off.
Witnesses said the rival camps had fired artillery shells and rockets into the air in shows of force for the second day running, sending hundreds of local residents fleeing for safety.
"Our mujahadeen are now ready in frontline trenches and all other fighters have reinforced the war zone because the enemy of Allah is keen on a full-scale attack," said Islamist commander Mursal Haji Ali.