A Somali armed group has told the Horn of Africa nation's embattled president to resign and said they had succeeded where the government had failed, in establishing order in areas they controlled.
Hizbul Islam, which has waged a three-year insurgency against the Western-backed interim government, urged Somalia's Muslims to unite and join the struggle against foreign forces.
"President Sheikh Sharif Ahmed ought to quit. He has nothing for the people except a call for more foreign troops that massacre Somalis," Sheikh Hassan Dahir Aweys, leader of Hizbul Islam, told reporters on Tuesday evening.
In recent days, the fighters have intensified their offensive on government targets and killed four Ugandan peacekeepers deployed near the presidential palace.
"I urge Islamists to unite. Areas under the control of Islamists are peaceful. They are the good Muslims who can rule the country," Aweys said.
A U.S. military official said on Wednesday that foreign fighters were not universally accepted by al Shabaab, but that outside powers would find it hard to use their presence to divide and weaken the insurgency.
More than 150 people have died over the last 10 days during the latest escalation of violence in Mogadishu, medics said. On Tuesday, a roadside blast and heavy artillery fire between insurgents and AU-backed government troops killed at least 18 people.
Ali Muse, coordinator of the ambulance service, said many of Tuesday's casualties were civilians hit by shells landing in and around the Bakara market, Mogadishu's largest bazaar and a known rebel stronghold.
Nine people were killed when a roadside bomb hit two minibuses, doctors at the Medina Hospital said.
"The bomb exploded on the buses ahead of the one I was on. Blood and pieces of human flesh littered the road," witness Ismail Musamil told Reuters.