Artillery shells and mortars rained down on Mogadishu Tuesday after a week of raging battles, despite a plea by UN Secretary General Ban Ki-moon to end the violence that local groups say has left nearly 300 people dead. Islamic insurgents clashed with allied Ethiopian and Somali government forces, using mortars and rocket propelled grenades against tanks and artillery positions in the north of the battle-scarred coastal city. A suspected suicide car bomb exploded outside an Ethiopian military base 30 kilometers (18 miles) from the capital, after troops opened fire on a minibus that was speeding toward their base, local resident Mayow Mohamed said. Three civilians were injured in the blast, and Ethiopian troops sealed off the area while black smoke billowed into the sky, he said. A big explosion outside Mogadishu's Ambassador Hotel wounded two civilians, Somali presidential spokesman Hussein Mohamoud Hussein said. The hotel is used by government lawmakers. Most of Tuesday's fighting was around front-line positions. Weary Mogadishu residents said it was not as fierce as in previous days. But since February more than 320,000 Somalis have fled the capital, the UN says. Some 293 civilians have been killed and 587 wounded, according to a local committee assessing damage from the worst fighting in more than 15 years. More than 82,000 people have fled the city since this latest fighting erupted on April 18, said Hussein Farah Siyad, a spokesman with Mogadishu's dominant clan - the Hawiye. The latest fighting came hours after the UN secretary-general called on the warring sides to "immediately cease all hostilities and to facilitate access for the delivery of urgently needed humanitarian assistance," spokeswoman Michele Montas said in a statement in New York. "He deplores the reported indiscriminate use of heavy weapons against civilian population centers, which is in disregard of international humanitarian law," the statement said. At least five people were wounded in Tuesday's clashes, said doctors at Mogadishu's largest medical center, the Medina Hospital, with deaths likely. The coastal city of Kismayo, 500 kilometers (310 miles) south of the capital, has fallen to a Somali clan with alleged ties to the defeated Islamic movement, remnants of which are fighting Ethiopian forces in the capital, said Marehan spokesman Mohamed Ali Hassan. The city fell late Monday after a bloody clash between two clans with at least 21 people killed and 17 wounded, he said. The United Nations said the fighting in Mogadishu had sparked the worst humanitarian crisis in the war-ravaged country's recent history, with many of the city's residents trapped because roads out of Mogadishu were blocked. "I do not think the fighting is as heavy as the past days because the sides have got tired so they need breathing space to replace their men and repair their damaged equipment," said local resident and eyewitness Abdi Ahemd Shoma. Rotting bodies have been left on the streets for days, witnesses said, as it is too dangerous to try to retrieve them. The top US diplomat for Africa, Jendayi Frazer, said late Monday the US was also deeply concerned by the fighting in the Somali capital but condemned Eritrea "because they continue to fund, arm, train and advise the insurgents." "We're pushing for the cease-fire...so that they can end this violence," she told reporters in Washington.