Somalia's deadliest ever attack, a truck bomb in the capital Mogadishu, has now killed 358 people with 228 more injured, the government has said, a major increase in the fatality toll.

A truck packed with explosives blew up in Hodan on 14 October, destroying some 20 buildings in the bustling commercial district.

It is believed the truck was carrying at least 500kg of explosives.

In a tweet Somali Minister of Information Abdirahman Osman said the latest number of casualties stands at 642 - of which 358 were killed, 228 were injured with 56 missing.

The figures mark a sharp increase in the toll, which earlier this week was put at 276 dead and 300 wounded. 

The attack has overwhelmed Somalia's fragile health system, and allies from the US, Qatar, Turkey and Kenya have sent planeloads of medical supplies as well as doctors, with all except the US also evacuating some of the wounded.

Death tolls are notoriously difficult to establish in Mogadishu, with families often quickly taking victims away to be buried.

There has been no immediate claim of responsibility, but al-Shabaab, a militant group aligned with al-Qaeda, carries out regular suicide bombings in Mogadishu in its bid to overthrow Somalia's internationally-backed government.

The group has a history of not claiming attacks whose scale provokes massive public outrage.