The report further alleges that al-Shabab, which is affiliated to al-Qaeda, has an annual revenue collection of about $180m.

Entitled Al-Shabab’s Arsenal - From Taxes to Terror, the report says the group uses various methods to procure weapons, including direct purchases from local black markets, and from arms traders contracted to buy and deliv­er weapons from abroad, mainly Yemen.

The Hiraal institute also says that the insurgents control large parts of Somalia and maintain a degree of influence on the populace through a mix of persuasion, administration and coercion.

The authors recommend several measures aimed at disrupting al-Shabab's weapons acquisition and movement, including countering arms imports from the Gulf of Aden.