At least three people were killed when a car bomb targeting military trainers from the UAE hit their convoy in the Somali capital but the officials were unharmed, police said on Wednesday.

The Islamist militant group al Shabaab claimed responsibility for the attack and said it carried out the attack and "inflicted casualties" without giving details.

Hussein Afrah, a Somali military officer, said those killed were Somali soldiers.

"The car bomb targeted UAE trainers in a bulletproof car. They are all safe," captain Afrah told Reuters.

"The incident took place near the military hospital where UAE trains Somali military. Three Somali military who were on the military pick up died and several other civilians who were passing by were injured," he added.

In the past, al Shabaab has exaggerated the number of government members it has killed, while officials have played down losses.

Major Farah Abdikadir, a police officer, said seven people were wounded in the blast.

A Reuters witness saw the ruined car in which the bomb had been detonated, a damaged military pick up and a pool of blood.

On Sunday, the group's fighters detonated a car bomb in the capital and shot their way into a national intelligence agency training site.

Four Islamist gunmen were killed, the internal security ministry said, adding that the government did not suffer any casualties during the attack. But the group's fighters said they had killed more than 10 intelligence officials.

An African Union Mission in Somalia (Amisom) and Somali army offensive last year pushed al Shabaab out of major strongholds, but the group still controls some rural areas from where it launches regular attacks in Somalia and neighbouring Kenya, which also has forces with Amisom.

On Monday and Tuesday, police said the group had killed six soldiers and an elder in separate incidents in the capital, the south central town of Beledweyne and the seaside town of Marka. Al Shabaab put the number of those killed at nine.-Reuters