A powerful blast has struck the commercial and administrative district of the Somali capital, Mogadishu, sending a plume of black smoke into the sky and killing 11 people, Al Jazeera's correspondent and police say.

The blast, claimed by al-Qaeda-linked al-Shabab rebels, struck Mogadishu's 'Kilometre 4' neighbourhood on Sunday morning, and targeted a convoy carrying Qatari officials through central Mogadishu.

The visiting delegation of Qataris, who were travelling in the Somali interior minister's bullet-proof vehicle, were "safe", a security officer told the Reuters news agency. The minister was not in the car at the time.

Al Jazeera's Peter Greste, reporting from Mogadishu, confirmed 11 people had been killed in the blast, the first major attack this month. He said he had seen at least three bodies.

"Four vehicles look like they are completely damaged," he said. 

A second explosion went off in Mogadishu but there were no immediate reports of casualties, said Greste.

Our correspondent added that the area targeted in Sunday's attack had been in lockdown in the past few days because of an "unspecified threat".

Last month nine fighters dressed in police uniforms attacked Mogadishu's court complex, killing 10 national security officers before entering the building.

In March a car bomb in Mogadishu killed 10 people, with al-Shabab claiming responsibility for the attack.

Although significantly weakened by foreign troops from the African Union, the group has continued to launch attacks in Mogadishu where peacekeepers and the army maintain security.

Somalia's new government is still rebuilding its army and police after decades of violence that began with the overthrow of President Siad Barre in 1991. 

Source: Al Jazeera And Agencies