<span style="color: #222222;">Mortar shells have exploded in the Somali capital, Mogadishu, as regional leaders gathered in the city to discuss their joint offensive against the al-Shabab militant group. The four shells hit areas near the heavily guarded presidential palace. There are no reports of casualties.<br />''<br />''The leaders of Kenya, Ethiopia and Djibouti are holding a summit there on Wednesday following recent military gains made by the Somali government against the Islamist militants. Al-Shabab still controls large areas of Somalia, and are continuing to carry out regular attacks.<br />''<br />''But they have lost territory since the government, backed by the US and African troops, launched a new offensive last August.</span><br />