A report from Arab media Asharq Al-Awsat says that guns supplied by Iran to its allied Houthi militias in Yemen are being smuggled across the Gulf of Aden to Somalia, according to a Geneva-based think tank, where al-Qaeda-linked al Shabab insurgents are battling a weak and divided government.

The Global Initiative against Transnational Organized Crime said its study drew on data from more than 400 weapons documented in 13 locations across Somalia over eight months and inventories from 13 dhows intercepted by naval vessels.

It is the first publicly available research into the scale of illicit arms smuggling from Yemen into the Horn of Africa country.

"Weapons originating in the Iran-Yemen arms trade are being trafficked onward into Somalia itself," said the study, which is due to be published on Wednesday.