One Hizbul Islam commander said he believed scores of gunmen had died in the battle.
Until the latest fighting, the two Islamist groups had shared control of the port, a lucrative source of taxes and other income.
Sheikh Hassan Yaqub, the spokesperson in Kismayu for al Shabaab, told Reuters by telephone his side’s forces were now in charge. Washington describes al Shabaab as al Qaeda’s proxy in the failed Horn of Africa state.
“Everything is going well now in Kismayu. The situation is completely calm, there are no problems,” Yaqub said.
“Many mujahideen died in the fighting, but we are providing medical care to our opponents who were injured.”
Hospital workers said more than 120 civilians were wounded.
Hizbul Islam fighters quit Kismayu for surrounding districts, and there were fears they would retaliate. But some of the hundreds of residents who had fled returned to their homes last week, and some businesses reopened their doors.
One Hizbul Islam commander told Reuters by telephone that the overall death toll from last week could be much higher.
Gunmen buried in alleys
Western donors have long hoped hardliners in al Shabaab could be isolated by a deal between more moderate Hizbul leaders and the government that could bring some stability to the country after nearly two decades of chaos.
President Sheikh Sharif Ahmed has so far failed to lure top Hizbul Islam figures to his side, but a feud between the two rebel groups could give his government some breathing space.
“Al Shabaab drove us out after seven hours of serious fighting,” the Hizbul commander, Mohamed Aden, said by phone from the Kismayu outskirts. “I’m sure more died, because each side was burying tens of its fighters like rubbish in the alleyways.”
Residents said foreign gunmen appeared to be among the dead.
Western security experts say Somalia has become a safe haven for militants, including foreign jihadists, who are using it to hide and plot attacks across the region and beyond.
Fighting in Somalia has killed nearly 19 000 civilians since the start of 2007 and driven 1.5 million from their homes.
The clashes between Somalia’s two main rebel groups raised the prospect of confrontations between their forces elsewhere including Mogadishu, where they have fought together against the weak UN-backed government and African Union peacekeepers.
Hizbul had said it would fight al Shabaab “everywhere” in Somalia if fighting broke out in Kismayu.
But al Shabaab’s main spokesman in the capital sought to downplay the risk and pinned the blame for the Kismayu bloodshed on a senior Hizbul commander there, Sheikh Ahmed Madobe.
“This conflict is not among the mujahideen,” the spokesman, Sheikh Ali Mohamud Rage, told reporters. “Sheikh Ahmed Madobe is the only one responsible for the war.”
Pic: Somali pirates