World leaders gather in London to attend a conference on ending two decades of turmoil in Somalia.

British Prime Minister David Cameron, who chaired the meeting, insisted the international community had a responsibility to act.

(SOUNDBITE) (English) BRITISH PRIME MINISTER DAVID CAMERON:

"In a country where there is so little hope, where there is chaos and violence and terrorism, pirates are disrupting vital trade routes and kidnapping tourists. Young minds are being poisoned by radicalism, breeding terrorism that is threatening not just Somalia but the whole world. If the rest of us just sit back and look on, we will pay a price for doing so."

Speaking on a panel that included the leader of Somalia's Transitional Federal Government, U.S. Secretary of State Hillary Clinton called for tough action.

(SOUNDBITE) (English) U.S. SECRETARY OF STATE HILLARY CLINTON:

"Attempts to obstruct progress and maintain the broken status quo will not be tolerated. We will encourage the international community to impose further sanctions including travel bans and asset freezes on people inside and outside the TFG who seek to undermine Somalia's peace and security or to delay or even prevent Somali's political transition."

Much of Somalia is controlled by Islamist rebels from the group known as 'Al Shabaab'.

The African state plunged into fighting between rival warlords, clans and factions after the president was overthrown in 1991 - with up to a million dying the ensuing chaos.

Armed gangs have thrived both on the mainland and at sea where Somali pirates have taken to hijacking ships on one of the world's busiest shipping lanes.

Simon Hanna, Reuters.