Osama bin Laden speaks in this 1998 file photo at a meeting at an undisclosed location in Afghanistan. The CIA has disbanded a unit set up in the 1990s to oversee the spy agency's hunt for Osama bin Laden and transferred its duties to broader operations that track Islamist militant groups, a US intelligence official said on Tuesday.  [AP]

The CIA has disbanded a unit set up in the 1990s to oversee the spy agency's hunt for Osama bin Laden and transferred its duties to broader operations that track Islamist militant groups, a US intelligence official said on Tuesday.

The bin Laden unit, codenamed Alec Station, became less valuable as a separate operation as counterterrorism operations eliminated top al Qaeda operatives and the movement's focus shifted more to regional networks of militants, said the official, who spoke on condition of anonymity.

"Al Qaeda is no longer the hierarchical organization that it was before 9-11. Three-quarters of its senior leaders have been killed or captured," said the official, referring to the US-led response to the September 11 attacks.

"What you have had since 9-11 is growth in the Islamic jihadist movement around the world among groups and individuals who may be associated with al Qaeda, and may have financial and operation links with al Qaeda, but have no command and control relationship with it," he added.

The official described the ending of the bin Laden unit as a "reallocation of resources" within the CIA's Counterterrorism Center. But he said the spy agency still has staff devoted full time to the tracking and analysis of intelligence related to bin Laden and other senior al Qaeda leaders.

"The bin Laden effort has been absorbed into a larger effort. It's now one part of an effort that looks at all of these jihadist organizations," the official said.

Alec Station, established in 1996 after bin Laden's initial calls for global jihad, employed about two dozen people. The operation was bolstered after the September 11 attacks on New York and Washington that killed about 3,000 people.

The New York Times reported on Tuesday that the bin Laden unit was disbanded late last year and quoted its first director, author Michael Scheuer, as predicting the move would denigrate the CIA's effort to find bin Laden.

The logo of the US Central Intelligence Agency is shown in the lobby of the CIA headquarters in Langley, Virginia in this March 3, 2005 file photo. The CIA has disbanded a unit set up in the 1990s to oversee the spy agency's hunt for Osama bin Laden and transferred its duties to broader operations that track Islamist militant groups, an intelligence official said on Tuesday. [Reuters]

Bin Laden and his second-in-command, Ayman al-Zawahri, are believed hiding in the mountains along the Afghanistan-Pakistan border.

John Negroponte, the US director of national intelligence, told the Senate in February that al Qaeda was a "battered" organization but that it remained the top concern for the intelligence community.

Negroponte noted the rise of other organizations inspired by al Qaeda. But he told the Senate Select Committee on Intelligence: "These groups pose less danger to the United States homeland than does al Qaeda, but they increasingly threaten our allies and interests abroad and are working to expand their reach and capabilities."

The Times said the decision to close the CIA's bin Laden unit was made by former Counterterrorism Center chief Robert Grenier, who decided the agency needed to reorganize to better address constant changes in terrorist organizations.