There were varied figures floated by the AMISOM and Al Shabaab Spokesman Abdiaziz Abu Musab who is known to exaggerate the number of troops killed, while AMISOM rarely gives exact figures.
Kenya’s Military Spokesman Col David Obonyo had earlier issued a brief statement on the attack but steered clear of the casualty figures, saying it was yet to be confirmed.
While Obonyo said the attack occurred at a Somalia National Army base, the statement from State House was categorical that it occurred at the AMISOM base at El Adde.
El Adde is occupied by Kenya Defence Forces (KDF) serving under AMISOM.
“Our gallant soldiers reacted swiftly to protect their camp; to protect their peace and stability that they are in Somalia to secure; and to protect our country from its enemies and their sympathizers,” the president said.
The attack came as politicians met in the southern port of Kismayu, with President Hassan Sheikh Mohamud leading a “National Consultative Forum” to debate planned elections due later this year.
“Somalia is no longer a failed state,” Mohamud said in a statement, which made no reference to the attack. “Somalia is building a strong foundation to support a better future.”
Local elder Hussein Adam said he heard a huge explosion followed by intense gunfire for about 45 minutes.
“We don’t know about the casualties, but people who went there saw many dead bodies strewn around,” he said, having spoken to those who went to the base.
Al Shabaab, fighting to overthrow Somalia’s internationally-backed and AU-protected government, has launched a string of similar attacks.
In September 2015, Al Shabaab fighters stormed a Ugandan AMISOM base in Janale district, 80 kilometres (50 miles) southwest of Mogadishu in the Lower Shabelle region.
And in June, Shabaab killed dozens of Burundian soldiers when they overran an AMISOM outpost northwest of Mogadishu.
The militants also stage frequent suicide attacks in the capital.
But the 22,000-strong AMISOM force has also made significant gains against the Sheba, pushing them out of several strongholds in the southwest.
The Shabaab have also staged attacks in Kenya, killing at least 67 people at Nairobi’s Westgate Mall in 2013 and massacring 148 people at a university in Garissa in April 2015.
The militants say the attacks are retaliation for the Kenyan military presence in Somalia and “war crimes” committed by Kenyan troops.