At least nine civilians were killed in bitter fighting Thursday between Ethiopian forces and Islamist insurgents in the Somali capital, including a possible suicide bombing on an army base.
One witness described seeing a suicide bomber detonate his car inside an Ethiopian base but officials could not confirm that the explosion was a kamikaze attack.
"I can tell you that a car has exploded inside the camp. It was a suicide bombing," said Sheikh Hassan, who lives on a rise overlooking the Aslubta camp, about seven kilometres (4.3 miles) southwest of Mogadishu.
Another resident, Ali Abdalla Mohamed, said: "It was a very heavy explosion and it came from Aslubta camp. I saw smoke coming out of the camp but I don't know the casualties."
Somali Deputy Defence Minister Salad Ali Jelle could not confirm that the blast was the work of a suicide bomber. There were no reports of casualties and Ethiopian troops were unavailable to comment.
Machinegun and heavy mortar fire battered several areas of the capital including the fortified presidential palace.
Witnesses said eight people were killed when a mortar shell hit a bus station in the south of the city.
"I have counted at least eight bodies, some of them dismembered," said witness Hussein Mohamed Abdi.
"They were innocent people who wanted to flee the town when they met death."
Another civilian was killed in Fagah district of northern Mogadishu when long-range shells crashed into residential areas, said resident Alaso Haji Warsame.
At least 12 civilians were wounded in the fighting but residents said the casualty figure could be higher as both sides fired unrelentingly. Many said they felt they were being targeted.
"We don't know why civilians are also being targeted. You see mortars and artillery shells landing everywhere and people are killed. May Allah save our souls," said Mohamed Sheikh Sudi, a driver.
At the same time as the blast at the military base, an Ethiopian military truck was blown apart by a landmine in Lasole area, about 18 kilometres (11 miles) south of the capital as an army convoy headed to Mogadishu, injuring two civilians in a minibus passing by, residents said.
Four days of fighting that broke out late last month was the worst violence in Mogadishu for 15 years and efforts to agree a lasting ceasefire have been dogged by clashes.
At least seven civilians were killed Tuesday and several houses destroyed when the rivals clashed in southern Mogadishu.
In Geneva, UN's humanitarian coordinator for Somalia Eric Laroche warned that a humanitarian catastrophe was looming in Somalia unless fighting subsided and access for relief aid is opened up, especially around Mogadishu.
"Unless something is done, the humanitarian crisis is going to turn into a catastrophe very soon," Laroche told journalists.
He said relief supplies were being blocked by government forces, UN aircraft were being shot at, corpses were lying in the streets of the capital, a cholera or diarrhea epidemic is taking hold and new flooding is likely soon.
Elders from Mogadishu's dominant Hawiye clan have unsuccessfully sought to end the fighting and have accused Ethiopian forces of breaking a truce they announced after last month's violence.
Hawiye elders say recent fighting has killed at least 1,000 people and wounded 4,000 others. The United Nations says at least 208,000 people have been displaced from the capital.
Ethiopian commanders have refused to meet again with the elders until guerrilla leaders agree to attend negotiations.
Addis Ababa deployed its forces to Somalia late last year to help the weak interim government oust the Islamist movement from the country's southern and central region.
Somalia, a nation of about 10 million, has lacked an effective government since the ousting of dictator Mohamed Siad Barre in 1991 touched off a power struggle that exploded into inter-clan warfare.