Somalia's much-delayed peace conference has gotten off to a rocky start with seven mortar shells exploding near the Mogadishu venue.
The meeting was then adjourned to give delegates more time to arrive.
President Abdullahi Yusuf Ahmed was addressing the conference at the time of the explosions, the nearest of which occurred about 500 metres away, but refused to cut off his speech.
"We cannot be terrified even if anti-peace elements throw an atomic bomb. I want to assure you the time of uncertainty and the use of force to pursue power is over," said the former warlord.
Police officer Ibrahim Dhagool said two shells exploded in Shibis district near the hall where Mr Yusuf was speaking, causing no injuries. Five other mortars hit a residential area, wounding three people.
Shortly afterwards, conference chief organiser Ali Mahdi Mohamed adjourned the talks to until Thursday to ensure delegates had arrived.
"Some did not arrive for logistical reasons," he said.
"The delegates will continue meeting informally to discuss on key issues. Today's adjournment was not caused by insecurity, but by the need to have everybody on board," he told AFP after the adjournment.
Officials said around 800 of the 1,325 invited delegates had registered at the venue in a police warehouse in northern Mogadishu.
"I urge you to rise above your respective clan and sub-clan (politics) in order to bring normality to our country," Mr Mohamed told delegates.
"This is a historic opportunity for you to have dialogue and reconciliation in Somalia. Most of the previous conferences were unsuccessful because they were held abroad."
Key officials at the meeting included Yusuf, parliament speaker Aden Mohamed Nur, Ethiopian minister Tekeda Alamu and Atalla Hamad el Bashir, head of the regional peacemaking bloc, the Inter-Governmental Authority on Development.
The virtually homeless government has failed to bring the restive country under control in its three years of existence.
It called the conference after it drove out Islamist militants from the capital with the help of Ethiopia in January. The Islamists leaders boycotting the meeting, which has already been delayed three times.
The Islamists, who want the talks held in a neutral country - and only after Ethiopian troops have pulled out of Somalia - vowed to attack the delegates in a new Internet message whose authenticity could not be confirmed.
"The alleged reconciliation conference is a link in the chain of efforts exerted by the crusaders to confer legitimacy on the (Ethiopian) occupying enemy," said a statement by the Young Mujahideen Movement and dated Friday.
Participants "must be targeted, whoever they are. Our long arm will reach (them) wherever they are, God willing," said the statement, posted on a website regularly used by Islamist militants.
Ethiopia-backed government troops had earlier sealed the conference venue, frisking pedestrians and searching vehicles while others took up positions around major hotels where delegates are staying.
But observers have said insurgent attacks could still thwart the talks, the latest in more than a dozen attempts to restore stability since the 1991 ouster of dictator Mohamed Siad Barre sparked a bloody power struggle.
Sporadic gunfire was heard in Mogadishu overnight and a senior official and a boy were killed in a roadside bomb attack outside the capital early Sunday which also injured three other people, police said.
Fearing a surge in violence, hundreds of Somali families have fled the capital over the past few days.
The conference was designed to discuss a power-sharing arrangement between four major clans and a smaller one.
The meeting's 11-point agenda includes discussions on clan talks, disarmament, the sharing of resources and the "nature and impact of radical Islam."
Roland Marchal, an expert from France's Centre d'Etudes et de Recherches Internationales, said the conference was taking place because the international community had requested it, but called the talks a non-starter.