UN chief Ban Ki-moon called Friday for urgent international aid for Somalia to head off the risk of warlords exploiting a power vacuum after the scheduled change of power in August. \"We urgently need assistance to avoid a power vacuum that warlords might exploit,\" Ban told delegates from more than 50 countries gathered in Istanbul for an international conference on Somalia. \"I urge donors to contribute to this critical effort. In the face of terrorism, piracy and drought, Somalia needs solidarity,\" he added. With the war-torn country\'s transitional body preparing to hand over power in August, nations had to do their part to build a steady government after two decades of instability, the UN secretary general said. \"The end of the transition marks the beginning of a new phase in the political process,\" he added. And the provisional constitution needed to be an inclusive one, he said. \"All Somalis, regardless of gender, clan, or political affiliation should be able to take part in elections.\" It was important, he said, to gain the confidence of the Somali population, especially in areas recovered from Shebab occupation. The Istanbul meeting comes as government troops backed by an African Union force and anti-Islamist militia attempt to defeat the Shebab, an insurgent group that has declared its allegiance to Al-Qaeda. Somali President Sharif Sheikh Ahmed spelt out the scale of the task that lay ahead for the Horn of Africa nation after two decades of conflict that has cost 400,000 lives since 1991. The country\'s infrastructure would have to be rebuilt, he said, adding: \"It is a costly matter and our resources are very limited.\" Host country Turkey, which launched a major aid initiative last year for Somalia to help it through its worst drought in decades, also stressed the need for immediate help. \"Somalia needs, more than ever, material aid,\" said Foreign Minister Ahmet Davutoglu. The aim was to set up a new state structure following the August handover of power that would allow for normal life to return for good in Somalia, he added. On the first day of the conference, Turkey\'s Deputy Prime Minister Bekir Bozdag said the Somali capital Mogadishu was now open for business, as pro-government forces had largely driven out Islamist insurgents. British Foreign Secretary William Hague, who was also attending the Istanbul conference, has underlined the improvement in the security situation in Mogadishu, saying three of his country\'s ministers have visited this year. But in a statement Thursday he added: \"All eyes are now on Somalia\'s leaders to ensure that they deliver a peaceful handover of power and succession when the transitional period formally ends in August.\" The Istanbul conference builds on a February gathering in London. The focus Friday was on aid to Somalia after senior officials, experts and businessmen discussed the practical details of developing water, energy, roads and sustainability the previous day. But lawmakers have struggled to meet the targets set by a \"roadmap\" signed by Somalia\'s disparate leaders for the formation of a government by August 20 to replace the weak transitional body in Mogadishu. Since the 1991 ouster of former president Mohamed Siad Barre, Somalia has been variously governed by ruthless warlords and militia groups, each controlling their own limited fiefdoms.