The al-Shabab extremist group says one of the two suicide car bombers who struck in Somalia's capital on Tuesday was a former legislator.

Al-Shabab's radio Andalus is reporting that 57-year-old Salah Badbado, who defected to the extremist group in 2010, carried out one of the bombings near a United Nations de-mining agency office and the African Union's main base in Mogadishu.

Authorities said the attack killed 13 people. Al-Shabab claimed responsibility for the attack.

Badbado had denounced Somali government leaders as "Western puppets" and lived in rebel-held areas.