The Somalia-based extremist group al-Shabab says it has stoned to death a woman accused of marrying 11 men.

The al-Qaida-linked group's radio arm Andalus reports that the stoning was carried out on Wednesday after an ad hoc al-Shabab court convicted the woman in Sablale town in Lower Shabelle region.

The report says masked men stoned to death 30-year-old Shukri Abdullahi Warsame in a public square.

The self-proclaimed judge said the woman had confessed to having secretly married 11 men in a row without seeking a divorce.

Al-Shabab has been fighting for years to impose a strict version of Islam in the long-chaotic Horn of Africa nation.

The group often executes suspected spies and people accused of adultery after convictions that human rights groups say lack the proper judiciary process.