Fifty countries and organisations were to gather in London on Tuesday for an international conference aimed at preventing Somalia from slipping back into abject lawlessness.
British Prime Minister David Cameron and Somali President Hassan Sheikh Mohamud are co-hosting the gathering, which hopes to bolster political stability in the conflict-battered Horn of Africa country.
"The Somalia conference in London aims to capitalise on the significant progress made over the past year and to agree coordinated international support for the government of Somalia's plans to build political stability by improving security, police, justice and public financial management systems," Britain's Foreign Office said.
Organisations such as the United Nations, the African Union, the International Monetary Fund and Somalia's neighbours are among those invited.
Kenyan President Uhuru Kenyatta, who faces international trial for crimes against humanity, was also invited and is in the British capital for the summit.
Somalia has been battered by conflict since 1991 but a new United Nations-backed government took power in September, ending more than a decade of transitional rule.
The Al-Qaeda-linked Shebab militant group were driven out of Mogadishu in August 2011 by a regional military offensive but have carried out a series of attacks in recent months.
Around 11 people were killed in the capital on Sunday when a suicide attacker rammed a car laden with explosives into a government convoy carrying officials from Qatar. No-one immediately claimed responsibility.
Large parts of the country remain carved up between rival militias who pay little heed to the weak central government, while pirates operating from the Somali coast are still a problem for international shipping.
The conference follows on from ones held in London in February 2012 and Istanbul four months later.
Cameron said despite the progress made by the Somali government since then, big challenges remained.
"Tragic and despicable" recent attacks on Mogadishu are a reminder of "how much work we still have to do", he said.
"The message at the second London summit will be clear: we will not allow Somalia to fall back. The Somali people are seizing the opportunity to forge a new future and we will support them every step of the way.
"Together I hope we can all get behind a long-term security plan that helps Somalia build up its army, its police and its judiciary; one that ends the Shebab's reign of terror forever.
"I hope we can work towards getting Somalia the vital finance it needs to deal with its debts.
"I also hope we can improve transparency and accountability so people know where resources are going.
"We also need to continue the process of rebuilding the Somali state in an inclusive way."
Kenyatta's participation in the conference comes as he prepares to go on trial in July at the International Criminal Court in The Hague for crimes against humanity related to post-election violence in 2007-08.
Britain, like the rest of the European Union and other Western powers, has a policy of only "essential contact" with anyone charged by the ICC.
A British government source said the invitation to Kenyatta, voted into power in the March elections, counted as essential contact.
"Kenya is a vital partner on Somalia, providing nearly 5,000 troops and hosting more Somali refugees than any other nation," a Downing Street spokesman told AFP.
"We therefore welcome the decision of the Kenyan government and President Kenyatta to attend this conference."
Mo Farah, the Somali-born athlete who won two long-distance track gold medals for Britain at the London 2012 Olympics, urged attendees to help his homeland get "back again to what it was".
"There's kids out there for 20 years have never seen peace and that really hurts because them kids don't know anything else," he said.