Mr bin Laden is the chief suspect of the US embassy bombings in Kenya and Tanzania last August, which claimed up to 250 lives.
The sources say Mr bin Laden has visited Somalia, and a "secure communication system" is being set up by his men in southern Somalia, possibly at the coastal town of Ras Kamboni, near Kenya. He went missing from his base camp in Afghanistan on February 13, and reports said he was heading for Somalia, Sudan or Yemen.
In early April, sources said US security officers were in Ras Kamboni, investigating the 20 March fatal shooting of a US aid worker, Deena Umbarger, in a tea shop by Islamic extremists. Ras Kamboni is known as a fundamentalist "no-go" area, used by the Al Ittihad movement, which has long been linked to Mr bin Laden.
A US diplomat said members of Al Ittihad had refused to hand over the identified killers, and US pressure on the local clan to afford some sort of retribution led to fighting last week. Armed groups of fundamentalists fled across the Kenyan border. Somalia was abandoned by the international community after a US-led military intervention in1992-93 failed to find a political solution, and resulted in the deaths of US troops, humanitarian workers and hundreds of Somalis.
The country is isolated from the world and without a government, now with almost nothing to offer its impoverished citizens - no public services, no ministries or civil servants, no border, air or coast controls, no immigration procedures, virtually no communications network, no national security forces and no national intelligence.
Somalia's state without a government has caused increasing anxiety, especially silnce the embassy bombings. Some 500 FBI agents investigated the bombs, and pointed to a terrorist cell operating in Nairobi and Mombasa, founded by Mr bin Laden in 1993. The US is helping Kenya to tighten international security, particularly on the porous Somali border and the coastline.
Whispered rumours of Mr bin Laden's presence are rife in Somalia, inside and outside Mogadishu. But they initially received little serious attention: why go to a place where anarchy offers no security to a man with a US $5m reward on his head?
If international terrorists are looking for state protection, Somalia certainly appears a poor option. Two recently allied Somali faction leaders tenuously control the destroyed capital, Mogadishu, and tension and fighting continues in some areas of southern Somalia. There is not much left of the original Somali state, with two regions, Somaliland and Puntland, declaring independence.
Mr bin Laden would be unlikely to risk asking for the protection of any one faction leader, in view of the shifting alliances.
But Louis Freeh, director of the Federal Bureau of Investigation, told the US Senate in February: "Loosely affiliated extremists" such as Mr bin Laden "may pose the most urgent threat because [they] bring together groups on an ad hoc, temporary basis". Their strength, he says, is in not maintaining a rigid, organisational structure, and in having a high degree of mobility.
So Somalia's total absence of state structures may be useful. And Somalia has changed since the 1991-94 years of political anarchy. In Mogadishu there is a new boom in private business because of relative security and the no-holds-barred war economy, financing the warlords. The business tsars, strongly linked to the Arab States and private Islamic banks, call the shots.
One faction leader, Hussein Aideed, son of the notorious General Mohamed Aideed who took on US forces, said he had told US officials that Mr bin Laden or his henchmen may be in southern Somalia, in the Gedo region, but were unlikely to be in Mogadishu. He said only an international investigation could throw up more definite information.
Diplomatic sources say the State Department has told Hussein Aideed that the US citizenship of his family would be revoked if there was any proven co-operation with Al Ittihad, or any known terrorist.Reuse content