At least 16 people have been killed in a car bomb explosion near the port in Somalia's capital Mogadishu, police said.

Abdikadir Abdirahman Adem, Mogadishu's Amin ambulance service director, said: "We assisted 48 wounded people and carried 16 others who were killed in the blast."

Police officer Major Ahmed Ibrahim said the attacker rammed an explosive-laden vehicle into the main entrance of the Mogadishu port, which is the largest in the country.

He added that the bomber targeted police officers in the tax and customs offices in the port but most of the victims turned out to be pedestrians and employees.

No group has claimed responsibility for the attack but al-Shabab frequently carries out such attacks in the country. Pictures posted on social media showed a cloud of smoke rising over the city.

An employee at the facility, Mohamed Hussein, said the blast was the work of a suicide bomber. He added: "A suicide car bomb hit the outer gate of the port. Gunfire followed the attack."

Al-Shabab's militancy reportedly aims to oust the African Union Peacekeepers and overthrow the government of Somalia that is backed by the West.