At least five people have been killed in a suicide bombing in the heart of the Somalia's capital, Mogadishu, officials have said.
A bomber blew himself up at the gates of the presidential palace, which correspondents say is one of the city's most closely guarded areas.
The Islamist militants al-Shabab said they carried out the bombing.
Since being pushed out of Mogadishu in August, the group has staged a number of deadly attacks in the city.
The bomber was wearing a jacket packed with explosives, Paddy Ankunda, the spokesperson for the African Union force in Somalia (Amisom), told the BBC.
At least seven other people were injured by the blast - although al-Shabab, which recently joined al-Qaeda, says it killed 17 people, and wounded 30 others, AFP news agency reports.
Mogadishu is mostly under the control of Amisom, working alongside Somali government soldiers.
The presidential palace is a heavily fortified compound where the most senior government officials, including the president, have their offices.
Correspondents say this latest attack could be a setback to attempts to fully secure the city.
Al-Shabab is under attack on several fronts, with troops from Kenya and Ethiopia also gaining ground recently.
But the group still controls much of southern and central Somalia.
Kenyan soldiers fighting al-Shabab in southern Somalia are being integrated into the AU force - boosting Amisom numbers to 17,731 from its current level of 12,000.