\Al Shabaab has stepped up its campaign of bombings and gun assaults in Mogadishu in recent months ahead of parliamentary elections which are expected to take place within weeks.
Col. Abdiqadir Hussein, a police officer, told Reuters the explosion had occurred near the parliament building, while another police officer, Major Hussein Nur, said the car bomb hit a military vehicle at a junction checkpoint.
"2 soldiers died and 5 others were injured," Nur said, adding police, military and security forces were on the scene when the attack occurred.
Al Shabaab, which once ruled much of Somalia, wants to topple the Western-backed government in Mogadishu and drive out African AMISOM peacekeepers made up of soldiers from Kenya, Djibouti, Uganda, Ethiopia and other African nations
The group's radio station Andalus said a suicide car bomb had been driven by "a mujahid" into Sayidka junction "where a convoy of the apostate government security forces were passing."
Sheikh Abdiasis Abu Musab, al Shabaab’s military operations spokesman told Reuters the group had killed 17 soldiers and injured more than 30 others in the attack.
The group usually gives far lower numbers of casualties on its side and much higher death tolls for the security forces.
Witnesses said security forces had sealed off the area and nearby roads were blocked following the bombing.
Much of Somalia has been in a state of lawlessness and chaos since the early 1990s following the toppling of military dictator Mohamed Siad Barre.
A central government backed by the west and AMISOM has tried to restore order and rebuild but it has struggled under relentless attacks by al Shabaab.
