Somalia's police chief says security forces have arrested five soldiers from the African Union multinational force in the country for allegedly selling military supplies in the capital.

Gen. Mohamed Sheikh Hassan says Somali forces raided a garage in which AU soldiers were thought to be selling military supplies including sandbags, telephones, ammunition boxes and fuel.

Nine Somali soldiers were also arrested.

Ahmed Ali Dahir, Somalia's attorney general, said soldiers engaging in the "illegal" trade would be prosecuted.

The AU mission in Somalia said it would confirm the "claims."

For years, AU forces have been accused of selling military supplies in black markets in the East African country, a charge denied by the 22,000-strong force.

The mission is helping the government against an insurgency by the Islamic extremist group al-Shabab.