An ad-hoc court set up by the hardline Islamist group Shebab had earlier this week found the four young men guilty of stealing mobile phones and guns from residents in several of the Somali capital's neighbourhoods.

"The amputations have been carried out as scheduled," a Shebab official told AFP on condition of anonymity.

Residents in the Sukahola neighbourhood gathered to watch the amputations, which took place shortly after 9:00 am (0600 GMT), but no cameras nor mobile phones were allowed.

While most of the political players in Somalia recognise Islam as the main source of legislation, the Shebab have always advocated a very strict interpretation of Sharia.

An alliance including the Shebab and hardline Islamists already controls and administers large swathes of southern Somalia, where courts impose tough sentences that have been condemned by international rights groups.

On Monday, Amnesty International issued a statement urging the Shebab not to carry out the sentences.

"We are appealing to Al-Shebab not to carry out these cruel, inhuman and degrading punishments," said Tawanda Hondora, the London-basded watchdog?s Africa Deputy Director.