A team from the US Federal Bureau of Investigation (FBI) has arrived in the Sudanese capital, Khartoum, to help with enquiries into a failed assassination attempt against the prime minister.

Abdalla Hamdok's convoy was attacked with explosives and gunfire on Monday.

It is not yet clear who was behind the attack and the arrival of the three US investigators follows a call from the Sudanese authorities for foreign assistance.

Mr Hamdok, an economist, was appointed to head the transitional government following the overthrow last April of the long-standing President, Omar al-Bashir.

Correspondents say there are concerns over Sudan's stability given some once powerful personalities are opposed to the widespread political and security reforms taking place.