At least 65 people were killed by a suicide bombing in Mogadishu. Al-Qaida's affiliate al-Shabaab took responsibility for the attack, which it said targeted Somali officials and soldiers from the African Union Mission in Somalia, known as AMISOM.
"Our mujahedin fighters have entered a place where ministers and AMISOM foreigners stay," the terrorist group said in a statement published by the online Long War Journal.
The online forum notes Tuesday's bombing was the worst such attack by al-Shabaab since 2006.
Al-Shabaab has solidified its position in southern Somalia, after pulling out of Mogadishu earlier this year.
British Middle East and North African Minister Alistair Burt said the "callous" attack by al-Shabaab is a blow to the war-torn nation.
"It comes at a time when the country should be coming together, both to deliver political progress and to bring aid and relief to those facing famine across the country," he said.
The militant group has moved to retake territory along the Somali border with Kenya. The Islamist militant group also is breaking up camps for Somalia famine victims, sending tens of thousands of people back to areas wracked by drought.
The British government recently issued a travel warning for the Kenyan-Somalia border after a French woman was abducted from her holiday home in northern Kenya.