West African regional group Ecowas says it will not lift the sanctions it imposed on Mali after the military coup there five weeks ago until a civilian prime minister has been nominated.

The announcement came shortly after Mali's new president was sworn in.

Bah Ndaw, a former defence minister, was picked by the coup leader, Colonel Assimi Goita, to head a transitional government until elections are held.

At a ceremony in the capital Bamako Col Goita was sworn in as the vice-president.

Correspondents say the new president's main challenges include reversing an economic slump and ending the jihadist and inter-communal violence in the north and central Mali.