Somalia’s Al-Qaeda allied Shebab insurgents fired mortars at the presidential palace in the capital overnight, killing six civilians in a camp for displaced people nearby.The hardline Islamist group said its salvo of "midnight mortar attacks” were targeted at the palace, and boasted of killing African Union and government soldiers.But AU force spokesman Paddy Ankunda said only civilians were killed, adding the shells missed the presidency by about 300 metres and hit one of the many crowded camps."A father, mother and two of their children have all died, after a mortar shell smashed into their hut, and another round killed two other civilians,” said Abdiwahid Mohamed, a witness."People were sleeping when the mortar shells started falling, it killed a number of civilians at a camp near the presidential palace,” said Colonel Bare Mohamed, a government security official.The presidency -- guarded by a 10,000-strong AU force -- has come under several recent attacks, including a suicide bomber attack claimed by the Shebab that killed five people last week."It’s the second attack on the presidential palace in a week, demonstrating the sheer impotence that is surrounding the weak apostate regime,” the insurgents said in a message posted on Twitter."In every alley, every corner and every lane of Mogadishu, a mujahid (Islamist fighter) lies in wait for them,” the rebels added. Muktar Ali, another witness, said at least six mortar shells hit around the camp for displaced people in war-wracked Mogadishu and three inside. Seven other people were injured.