A lawmaker and his driver have been killed after a powerful car bomb exploded outside prime minister's office in Somali capital city of Mogadishu, security sources say.

The lawmaker identified as Warsame Faysal and his driver were killed in the blast that rocked the entrance of the presidential palace in Mogadishu on Friday.

Local security officials say the explosives were planted under the car and went off when the driver entered the vehicle.

No group or person has yet claimed responsibility for the deadly attack, but al-Shabab militant group has been blamed for such attacks in the past.

Violence in Somalia has been on the rise ahead of the elections in January.

On Thursday, a vehicle packed with explosives rammed into two pick-up trucks carrying Marine Forces in a busy market area in the northern Puntland region, leaving nine people dead and nearly 40 others injured.

The al-Qaeda-linked militants have been driven out of Somalia's major towns by an 18,000-strong UN-mandated African Union force, known as AMISOM. AMISOM is made up of troops from Uganda, Burundi, Djibouti, Sierra Leone and Kenya.

The United Nations Secretary-General Ban Ki-moon has recently warned about the deteriorating security situation in Somalia, saying the African country may slide back into being a failed state.

Somalia did not have an effective central government from 1991 until August 2012. In September 2012, MPs meeting in Mogadishu elected Sheikh Mohamud as the new president of Somalia with a big majority.