By Abdi Sheikh and Feisal Omar
MOGADISHU (Reuters) - Two suicide bombers attacked a conference in Somalia on Wednesday but failed to stop delegates agreeing a new draft constitution that is meant to help the violence-torn East African country return to stability.
One bomber killed six security officers, while the other was shot and killed before he could detonate his bomb, police said.
Al Shabaab, Somalia's al Qaeda-linked group, said it was behind the attack and that it had succeeded in killing Somali and African Union troops.
"The two bombers wore government uniform," Colonel Mohamed Ali, a police officer, told Reuters.
"One jumped over a wall opposite the conference building but he was shot dead outside the gate. Then another bomber jumped from another wall and his bomb exploded where government soldiers stood."
Delegates at the Mogadishu conference continued with their discussions and later adopted a provisional constitution, seen as a step forward on the road to national recovery.
"We were behind the bombing. Two Mujahideen suicide bombers did it. We have killed a number of AMISOM and Somali troops," Sheikh Abdiasis Abu Musab, the spokesman for Al Shabaab's military operation told Reuters.
"We had also targeted the conference with a landmine explosion before. We shall target the constitution conference and its members one by one."
Although weakened, al Shabaab is the most powerful of an array of militias spawned by the conflict in Somalia, where armed groups have a history of wrecking attempted political settlements and perpetuating war, instability and famine.
The African Union's peacekeeping force in Somalia hopes to drive the militants out of the country's central and southern regions this month, when the U.N.-backed government's mandate expires.
Under the terms of a political road map, Somalia must establish a legitimate government seen as inclusive by the country's fractious clans, as well as a new parliament and constituent assembly to replace institutions plagued by corruption and infighting.
The 825-member National Constituent Assembly, which has been sitting in Mogadishu for the last week, approved the provisional constitution by a show of hands.
It will replace an 8-year old Transitional Federal Charter and lead to the conclusion of the transition process on August 20.
The Special Representative of the Chairperson of the African Union Commission for Somalia, Boubacar Diarra, said the draft would be subjected to a nationwide referendum as soon as the security situation improved.
"Today is the culmination of years of hard work by the Somali people with the support of the international community," Diarra said in a statement.
Al Shabaab was driven out of Mogadishu late last year and is struggling to hold on to territory elsewhere in the face of attacks by Kenyan, Ethiopian and African Union forces trying to prevent Islamist militancy spreading out from Somalia.
(Additional reporting by Mohamed Ahmed; Writing by James Macharia; Editing by Robin Pomeroy)