(This version of the March 1st story corrects AFRICOM to AMISOM in the second paragraph)

MOGADISHU (Reuters) - A mortar attack in the Somali capital Mogadishu, claimed by Islamist group al Shabaab, killed three civilians and injured two others on Thursday, the African Union peacekeeping force AMISOM said.

The mortar rounds were fired near a stadium, Lieutenant Colonel Wilson Rono, AMISOM spokesman, told Reuters.

Earlier on Thursday, al Shabaab militants set off a suicide car bomb at a checkpoint about 15 km (nine miles) outside the capital. At least five people were injured including soldiers, police officer Ali Roble told Reuters.

A second police officer, Abdullahi Nur, told Reuters that many vehicles had been parked at the checkpoint for inspection when the blast occurred.

Al Shabaab frequently carries out bombings in Mogadishu and elsewhere in Somalia in their effort to bring down the Western-backed federal government and drive out the AMISOM forces defending it.

On Friday, twin car bomb blasts in Mogadishu - claimed by al Shabaab - killed 45 people.

Abdiasis Abu Musab, al Shabaab’s military operations spokesman, told Reuters the group was responsible for both the mortar attack and the car bombing.