SOMALI BOMBING: "The suicide bomber was a young, slim lady with plaited hair"

Six people, including two of Somalia's top Olympics officials, were killed when a female suicide bomber struck a ceremony at Mogadishu's national theatre in an attack Islamist rebels said was aimed at assassinating government ministers.

Al Shabaab insurgents claimed responsibility for the blast on Wednesday that killed the heads of Somalia's soccer federation and Olympic committee in yet another stark reminder of the fragile security in the capital Mogadishu.

The bombing was an apparent attempt to kill the prime minister as he spoke at an event to mark the first anniversary of the country's new satellite television channel.

While the al Qaeda-allied militants pulled their fighters out of the capital last August, they have struck targets regularly in the heart of the coastal city using roadside bombs, mortars and suicide bombers.

A soldier guarding the newly-opened theatre said the bomber had been stopped but the premier's security team had insisted she be allowed in because she was carrying police ID.

"The suicide bomber was a young, slim lady with plaited hair. She wore a veil and carried a police identity card," Mohamed Ali, the soldier told Reuters.

"She sat under the tree in front of the theatre for a while. She stood and went towards the theatre when she heard the voice of the PM. We were suspicious and shouted 'stop'. She wanted to target the PM.

"We stopped her. But the PM's guards inside shouted 'let her come in' because she had a police identity card in her hand. And all of a sudden we heard the explosion."

The African Union, which also identified the bomber as a woman, said six people were killed and 12 wounded.

"The prime minister was speaking inside the theatre when the blast took place, but he is safe, unhurt," Gilbert Nitunga, deputy spokesman for the AU's AMISOM force, said.